Abutilon abutiloides (Jacq.) Strong. [A. californicum Benth. sensu f=Malvaceae Mallow 
Abutilon incanum (Link) Sweet. Indian mallow, pelotazo. Widespread f=Malvaceae Mallow 
Abutilon malacum Wats. Indian mallow. Scattered subshrub; common on f=Malvaceae Mallow 
Abutilon parishii Wats. Pima indian mallow. Scattered herbaceous perennial; f=Malvaceae Mallow 
Abutilon parvulum Gray. Indian mallow. Local herbaceous perennial; f=Malvaceae Mallow 
Acacia angustissima (Mill.) Kuntze. White ball acacia, fern acacia. f=Leguminosae Pea 
Acacia constricta Benth. Whitethorn acacia. Widespread shrub; very f=Leguminosae Pea 
Acacia farnesiana (L.) Willd. [A. minuta (M. E. Jones) Beauch., A. f=Leguminosae Pea 
Acacia greggii Gray. Catclaw acacia. Widespread shrub; very common f=Leguminosae Pea 
Acourtia nana (Gray) Reveal & King. [Perezia nana Gray]. Desert f=Compositae Sunflower 
Acourtia wrightii (Gray) Reveal & King. [Perezia wrightii Gray]. f=Compositae Sunflower 
Agave americana L. var. expansa  f=Agavaceae Agave 
Agave schotti  f=Agavaceae Agave 
Allionia incarnata L. Trailing four & o'clock, windmills. Widespread f=Nyctaginaceae Four o'clock 
Allium macropetalum Rydb. Wild onion. Scattered herbaceous perennial; f=Liliaceae Lily 
Aloysia wrightii (Gray) Heller. Oreganillo. Widespread shrub; common f=Verbenaceae Vervain 
Amaranthus fimbriatus  f=Amaranthaceae Amaranth 
Amaranthus fimbriatus f=Amaranthaceae Amaranth 
Amaranthus palmeri  f=Amaranthaceae Amaranth 
Amaranthus sp. nov.  f=Amaranthaceae Amaranth 
Ambrosia ambrosioides (Cav.) Payne. [Franseria ambrosioides Cav.]. f=Compositae Sunflower 
Ambrosia confertiflora DC. [Franseria confertiflora (DC.) Rydb.]. f=Compositae Sunflower 
Ambrosia cordifolia (Gray) Payne. [Franseria cordifolia Gray]. Sonoran f=Compositae Sunflower 
Ambrosia deltoidea (Torr.) Payne. [Franseria deltoidea Torr.]. Triangleleaf f=Compositae Sunflower 
Ambrosia dumosa (Gray) Payne. [Franseria dumosa Gray]. White bursage, f=Compositae Sunflower 
Amsinckia intermedia F. & M. Fiddleneck. Widespread annual; very f=Boraginaceae Borage 
Amsinckia tessellata Gray. Fiddleneck. Local annual; rare along sandy f=Boraginaceae Borage 
Androsace occidentalis Pursh. Scattered annual; common on rocky slopes f=Primulaceae Primrose 
Anemone tuberosa Rydb. Windflower, desert anemone. Widespread herbaceous f=Ranunculaceae Crowfoot 
Anisacanthus thurberi  f=Acanthaceae Acanthus 
Anoda pentaschista Gray. Local annual; uncommon on rocky slopes, Tumamoc f=Malvaceae Mallow 
Antirrhinum nuttallianum Benth. Nuttall snapdragon. Local annual; f=Scrophulariaceae Figwort 
Apium leptophyllum (Pers.) F. Muell. Wild celery. Local exotic annual; f=Umbelliferae Parsley 
Apodanthera undulata Gray. Coyote melon, Melon loco. Local herbaceous f=Cucurbitaceae Gourd 
Arabis perennans Wats. Rock cress. Widespread herbaceous perennial; f=Cruciferae Mustard 
Argemone gracilenta Greene. Crested prickly poppy. Widespread annual; f=Papaveraceae Poppy 
Argemone ochroleuca Sweet. [Argemone mexicana sensu K. & P.]. f=Papaveraceae Poppy 
Aristida adscensionis L. Six weeks threeawn. Widespread annual; very f=Gramineae Grass 
Aristida hamulosa Henr. Threeawn spider grass. Widespread perennial; f=Gramineae Grass 
Aristida parishii A. S. Hitchc. Threeawn. Scattered perennial; common f=Gramineae Grass 
Aristida purpurea Nutt. var. longiseta (Steud.) Vasey. Red threeawn. f=Gramineae Grass 
Aristida purpurea Nutt. var. nealleyi (Vasey) Allred. [A. glauca (Nees) f=Gramineae Grass 
Aristida purpurea Nutt. var. purpurea Nutt. Purple threeawn. Widespread f=Gramineae Grass 
Aristida ternipes Cav. Spider grass. Widespread perennial; common f=Gramineae Grass 
Aristolochia watsoni  f=Aristolochiaceae Birthwort 
Artemisia ludoviciana Nutt. ssp. albula (Wooton) Keck. White sage. f=Compositae Sunflower 
Artemisia ludoviciana Nutt. ssp. sulcata (Rydb.) Keck. White sage. f=Compositae Sunflower 
Arundo donax L. Giant cane. Local exotic perennial; uncommon on seep f=Gramineae Grass 
Asclepias nyctaginfolia Gray. Four o'clock milkweed. Local herbaceous f=Asclepiadaceae Milkweed 
Aster subulatus Michx. var. ligulatus Shinners. [A. exilis Ell.]. f=Compositae Sunflower 
Astragalus allochrous Gray var. playanus (M. E. Jones) Isely. [A. wootonii f=Leguminosae Pea 
Astragalus arizonicus Gray. Local herbaceous perennial; uncommon on f=Leguminosae Pea 
Astragalus didymocarpus H. & A. var. dispermus (Gray) Jeps. Local f=Leguminosae Pea 
Astragalus lentiginosus Dougl. var. australis Barneby. Locoweed. Scattered f=Leguminosae Pea 
Astragalus nuttallianus DC. var. austrinus (Small) Barneby. Locoweed. f=Leguminosae Pea 
Atriplex canescens (Pursh) Nutt. Fourwing Saltbush, wingscale. Scattered f=Chenopodiaceae Goosefoot 
Atriplex elegans (Moq.) D. Dietr. ssp. elegans. Scattered annual or f=Chenopodiaceae Goosefoot 
Atriplex linearis Wats. [A. canescens (Pursh) Nutt. ssp. linearis f=Chenopodiaceae Goosefoot 
Atriplex polycarpa (Torr.) Wats. Allscale. Local shrub; rare, jct. f=Chenopodiaceae Goosefoot 
Avena fatua L. Wild oat. Scattered exotic annual; uncommon on rocky f=Gramineae Grass 
Ayenia filiformis Wats. [A. compacta L., A. pusilla L. sensu K. & f=Sterculiaceae Cacao 
Ayenia microphylla Gray. Widespread subshrub; common on rocky slopes f=Sterculiaceae Cacao 
Baccharis brachyphylla Gray. Shortleaf baccharis. Local shrub; rare f=Compositae Sunflower 
Baccharis salicifolia (R. & P.) Pers. [B. glutinosa Pers.]. Seep f=Compositae Sunflower 
Baccharis sarothroides Gray. Desert broom. Widespread shrub; very f=Compositae Sunflower 
Bahia absinthifolia Benth. Widespread herbaceous perennial; common f=Compositae Sunflower 
Baileya multiradiata Harv. & Gray. Desert marigold. Scattered f=Compositae Sunflower 
Bebbia juncea (Benth.) Greene. var. aspera Greene. Sweetbush, chuckwalla's f=Compositae Sunflower 
Boerhaavia coccinea Mill. Red spiderling. Scattered herbaceous perennial; f=Nyctaginaceae Four o'clock 
Boerhaavia coulteri (Hook. f.) Wats. Spiderling. Local annual; uncommon f=Nyctaginaceae Four o'clock 
Boerhaavia erecta L. var. erecta. Spiderling. Local annual; uncommon f=Nyctaginaceae Four o'clock 
Boerhaavia erecta L. var. intermedia (Jones) K. & P. [B. intermedia f=Nyctaginaceae Four o'clock 
Boerhaavia gracillima Heimerl. Spiderling. Local herbaceous perennial; f=Nyctaginaceae Four o'clock 
Boerhaavia megaptera Standl. Winged spiderling. Scattered annual; f=Nyctaginaceae Four o'clock 
Boerhaavia spicata Choisy. Spiderling. Local annual; very common on f=Nyctaginaceae Four o'clock 
Boerhaavia wrightii Gray. Fourwing spiderling. Scattered annual; common f=Nyctaginaceae Four o'clock 
Bothriochloa barbinodis (Lag.) Herter. [Andropogon barbinodis Lag.]. f=Gramineae Grass 
Bothriochloa ischaemum (L.) Keng. King Ranch bluestem. [Andropogon f=Gramineae Grass 
Bouteloua aristidoides (H.B.K.) Griseb. Six weeks needle grama. Widespread f=Gramineae Grass 
Bouteloua barbata Lag. Six weeks grama. Scattered annual; uncommon f=Gramineae Grass 
Bouteloua chondrosioides (H.B.K.) Benth. Sprucetop grama. Local perennial; f=Gramineae Grass 
Bouteloua curtipendula (Michx.) Torr. Sideoats grama. Widespread perennial; f=Gramineae Grass 
Bouteloua eriopoda (Torr.) Torr. Black grama. Local perennial; common f=Gramineae Grass 
Bouteloua gracilis (H.B.K.) Lag. ex Steud. Blue grama. Local perennial; f=Gramineae Grass 
Bouteloua hirsuta Lag. Hairy grama. Local perennial; very common on f=Gramineae Grass 
Bouteloua repens (H.B.K.) Scribn. & Merr. [B. filiformis (Fourn.) f=Gramineae Grass 
Bouteloua rothrockii Vasey. Rothrock grama. Local perennial; uncommon f=Gramineae Grass 
Bouteloua trifida Thurb. Red grama. Scattered perennial; uncommon f=Gramineae Grass 
Bowlesia incana Ruiz & Pavon. Widespread annual; abundant on rocky f=Umbelliferae Parsley 
Brachiaria arizonica (Scribn. & Merr.) S. T. Blake. [Panicum arizonicum f=Gramineae Grass 
Brassica campestris L. Field mustard. Local exotic annual; rare (single f=Cruciferae Mustard 
Brassica eruca L. [Eruca sativa Mill.]. Local exotic annual; rare on f=Cruciferae Mustard 
Brassica nigra L. Koch. Black mustard. Local exotic annual; vicinity f=Cruciferae Mustard 
Brassica tournefortii Gouan. Mustard. Scattered exotic annual; common f=Cruciferae Mustard 
Brickellia baccharidea Gray. Brickell & bush. Local subshrub; f=Compositae Sunflower 
Brickellia californica (T. & G.) Gray. Brickell & bush. Scattered f=Compositae Sunflower 
Brickellia coulteri Gray. Brickell & bush. Widespread herbaceous f=Compositae Sunflower 
Bromus carinatus H. & A. [incl. B. arizonicus (Shear) Stebbins]. f=Gramineae Grass 
Bromus catharticus Vahl. [B. willdenowii Kunth]. Rescue grass. Local f=Gramineae Grass 
Bromus diandrus Roth. Local exotic?? annual; common on disturbed roadside f=Gramineae Grass 
Bromus rubens L. Foxtail chess; red brome. Widespread exotic annual; f=Gramineae Grass 
Bromus tectorum L. Cheat grass; downy chess. Local exotic annual; f=Gramineae Grass 
Caesalpinia gilliesii Wall. Yellow bird & of & paradise. Local f=Leguminosae Pea 
Calandrinia ciliata (R. & P.) DC. Red maids. Local annual; rare f=Portulacaceae Portulaca 
Calliandra eriophylla Benth. Fairy duster. Widespread shrub; very f=Leguminosae Pea 
Calliandra schottii Torr. [Zapoteca formosa (Kunth) H. Hern. ssp. schottii f=Leguminosae Pea 
Calochortus kennedyi Porter. Desert mariposa lily. Scattered herbaceous f=Liliaceae Lily 
Calycoseris parryi Gray. Yellow Tack stem. Local annual; uncommon f=Compositae Sunflower 
Calycoseris wrightii Gray. Tackstem. Scattered annual; uncommon (very f=Compositae Sunflower 
Calyptridium monandrum Nutt. Sand cress. Local annual; common on rocky f=Portulacaceae Portulaca 
Camissonia californica (Nutt. ex Torr. & Gray) Raven. [Oenothera f=Onagraceae Evening Primrose 
Camissonia chamaenerioides (Gray) Raven. [Oenothera chamaeneriodes f=Onagraceae Evening Primrose 
Camissonia clavaeformis (Torr. & Frem.) Raven. [Oenothera clavaeformis f=Onagraceae Evening Primrose 
Cannabis sativa L. Marijuana, hemp. Local exotic annual; rare in disturbed f=Cactaceae Cactus 
Capsella bursa-pastoris (L.) Medic. Shepherd's purse. Local exotic f=Cruciferae Mustard 
Carlowrightia arizonica  f=Acanthaceae Acanthus 
Carnegiea gigantea (Engelm.) Britt. & Rose. [Cereus giganteus f=Cactaceae Cactus 
Cassia artemisioides Gaud. Feathery cassia. Local exotic shrub; rare f=Leguminosae Pea 
Caulanthus lasiophyllus (H. & A.) Payson. [Thelypodium lasiophyllum f=Cruciferae Mustard 
Celtis pallida Torr. Desert hackberry. Widespread shrub; common on f=Ulmaceae Elm 
Centaurea melitensis L. Malta starthistle. Scattered exotic annual; f=Compositae Sunflower 
Centaurium calycosum (Buckl.) Fern. Centaury. Local annual; common f=Gentianaceae Gentian 
Cercidium floridum Benth. Blue paloverde. Scattered tree; common along f=Leguminosae Pea 
Cercidium floridum Benth. x Parkinsonia aculeata L. Hybrid paloverde.</li f=Leguminosae Pea 
Cercidium microphyllum (Torr.) Rose &amp; Johnst. Foothills paloverde. f=Leguminosae Pea 
Cercidium microphyllum (Torr.) Rose &amp; Johnst. X Parkinsonia aculeata f=Leguminosae Pea 
Chaenactis carphoclinia Gray. Pincushion flower. Local annual; rare f=Compositae Sunflower 
Chaenactis stevioides H. &amp; A. Pincushion flower. Widespread annual; f=Compositae Sunflower 
Cheilanthes lindheimeri  f=Adiantaceae Fern 
Cheilanthes parryi f=Adiantaceae Fern 
Cheilanthes pringlei  f=Adiantaceae Fern 
Cheilanthes wootonii  f=Adiantaceae Fern 
Cheilanthes wrightii  f=Adiantaceae Fern 
Cheilanthes yavapensis  f=Adiantaceae Fern 
Chenopodium berlandieri Moq. Pitseed goosefoot. Local annual; rare f=Chenopodiaceae Goosefoot 
Chenopodium incanum (Wats.) Heller. [C. fremontii Wats. var. incanum f=Chenopodiaceae Goosefoot 
Chenopodium murale L. Nettleleaf goosefoot. Local exotic annual; rare f=Chenopodiaceae Goosefoot 
Chenopodium neomexicanum Standl. New Mexican goosefoot. Widespread f=Chenopodiaceae Goosefoot 
Chilopsis linearis (Cav.) Sweet. Desert willow. Local shrub; uncommon f=Bignoniaceae Bignonia 
Chloris virgata Swartz. Feather fingergrass. Widespread annual; uncommon f=Gramineae Grass 
Chorizanthe brevicornu Torr. Brittle spineflower. Scattered annual; f=Polygonaceae Buckwheat 
Chorizanthe rigida (Torr.) T. &amp; G. Rigid spineflower. Local annual; f=Polygonaceae Buckwheat 
Cirsium neomexicanum Gray. Thistle. Scattered herbaceous perennial f=Compositae Sunflower 
Citrullis vulgaris Schrad. Watermelon. Local exotic annual; rare in f=Cucurbitaceae Gourd 
Clematis drummondii T. &amp; G. Texas virgin's bower, barbas de chivato. f=Ranunculaceae Crowfoot 
Commicarpus scandens (L.) Standl. Bush spiderling. Widespread subshrub; f=Nyctaginaceae Four o'clock 
Condalia correllii M. C. Johnst. Bluewood. Local shrub; under cliff f=Rhamnaceae Buckthorn 
Condalia warnockii M. C. Johnst. Mexican crucillo. [Condalia spathulata f=Rhamnaceae Buckthorn 
Convolvulus arvensis L. Field bindweed. Local exotic herbaceous perennial; f=Convolvulaceae Morning Glory 
Conyza bonariensis (L.) Cronq. [Erigeron linifolius Willd.]. Local f=Compositae Sunflower 
Conyza canadensis (L.) Cronq. [Erigeron canadensis L.]. Horseweed. f=Compositae Sunflower 
Conyza coulteri Gray. [Laennecia coulteri (A. Gray) Nesom]. Local f=Compositae Sunflower 
Coriandrum sativum L. Cilantro, coriander. Local exotic annual; Snyder f=Umbelliferae Parsley 
Cortaderia selloana (Schult.) Asch. &amp; Graebn. Pampas grass. Local f=Gramineae Grass 
Cottea pappophoroides Kunth. Cotta grass. Scattered perennial; uncommon f=Gramineae Grass 
Coursetia glandulosa Gray. [C. microphylla Gray]. Baby bonnets. Local f=Leguminosae Pea 
Crossosoma bigelovii Wats. Ragged rockflower. Widespread shrub; common f=Crossosomataceae Crossosoma 
Cryptantha angustifolia (Torr.) Greene. Narrowleaf nievitas. Local f=Boraginaceae Borage 
Cryptantha barbigera (Gray) Greene. Bearded nievitas. Widespread annual; f=Boraginaceae Borage 
Cryptantha decipiens (Jones) Heller. Gravel nievitas. Local annual; f=Boraginaceae Borage 
Cryptantha maritima Greene. Whitehair nievitas. Local annual; common f=Boraginaceae Borage 
Cryptantha micrantha (Torr.) Johnst. Purpleroot nievitas. Local annual; f=Boraginaceae Borage 
Cryptantha nevadensis Nels. &amp; Kenn. Nevada nievitas. Scattered f=Boraginaceae Borage 
Cryptantha pterocarya (Torr.) Greene. Wingnut nievitas. Widespread f=Boraginaceae Borage 
Cucurbita digitata Gray. Coyote gourd. Scattered herbaceous perennial f=Cucurbitaceae Gourd 
Cuscuta salina Engelm. Dodder. Local annual parasite; mesas, near f=Cuscutaceae Dodder 
Cuscuta tuberculata Brandegee. Dodder. Local annual parasite on Boerhaavia f=Cuscutaceae Dodder 
Cuscuta umbellata H.B.K. var. reflexa (Coult.) Yunker. Dodder. Local f=Cuscutaceae Dodder 
Cuscuta umbellata H.B.K. var. umbellata. Dodder. Local annual parasite f=Cuscutaceae Dodder 
Cynanchum arizonicum (Gray) Shinners. [Metastelma arizonicum Gray]. f=Asclepiadaceae Milkweed 
Cynodon dactylon (L.) Pers. Bermuda grass. Scattered exotic perennial; f=Gramineae Grass 
Cyperus alternifolius L. Flat sedge. Local exotic herbaceous perennial; f=Cyperaceae Sedge 
Cyperus esculentus L. Yellow nutsedge. Local herbaceous perennial; f=Cyperaceae Sedge 
Cyperus rotundus L. Purple nutsedge. Local exotic herbaceous perennial; f=Cyperaceae Sedge 
Cyperus squarrosus L. [Cyperus aristatus Rottb.]. Flatsedge. Local f=Cyperaceae Sedge 
Dalea grayi (Vail) L. O. Williams. Local herbaceous perennial; rare f=Leguminosae Pea 
Dalea neomexicana (Gray) Cory. Local herbaceous perennial; common onsandy f=Leguminosae Pea 
Dalea pogonathera Gray. Hierba del corazon. Local herbaceous perennial; f=Leguminosae Pea 
Dalea pringlei Gray. Pringle indigo bush. Local herbaceous perennial; f=Leguminosae Pea 
Dalea wrightii Gray. Local herbaceous perennial; common on rocky slopes f=Leguminosae Pea 
Dasylirion wheeleri  f=Agavaceae Agave 
Datura discolor Bernh. Desert thorn apple. Local annual; uncommon f=Solanaceae Potato, Nightshade 
Datura wrightii Regel. [D. meteloides DC.]. Sacred datura, moon flower. f=Solanaceae Potato, Nightshade 
Daucus pusillus Michx. Wild carrot. Widespread annual; common on rocky f=Umbelliferae Parsley 
Delphinium scaposum Greene. Barestem larkspur. Widespread herbaceous f=Ranunculaceae Crowfoot 
Descurainia pinnata (Walt.) Britt. Tansy mustard. Widespread annual; f=Cruciferae Mustard 
Descurainia sophia (L.) Webb. Flixweed. Local exotic annual; rare f=Cruciferae Mustard 
Desmanthus covillei (Britt. &amp; Rose) Wiggins ex Turner. Bundleflower. f=Leguminosae Pea 
Desmodium procumbens (Mill.) A. S. Hitchc. var. exigua (A. Gray) Shubert. f=Leguminosae Pea 
Dichelostemma pulchellum (Salisb.) Heller. Bluedick. Widespread herbaceous f=Liliaceae Lily 
Digitaria californica (Benth.) Henr. [Trichachne californica (Benth.) f=Gramineae Grass 
Digitaria insularis (L.) Mez ex Ekman. [Trichachne insularis (L.) f=Gramineae Grass 
Dimorphotheca sinuata DC. [D. aurantiaca Hort., not DC.]. African f=Compositae Sunflower 
Dodonaea viscosa Jacq. Hopbush. Local shrub; rare, single plant on f=Sapindaceae Soapberry 
Draba cuneifolia Nutt. Whitlow grass. Widespread annual; common on f=Cruciferae Mustard 
Dryopetalon runcinatum Gray. Scattered annual; common on rocky slopes f=Cruciferae Mustard 
Dyssodia acerosa DC. [Thymophylla acerosa (DC.) Strother]. Local subshrub; f=Compositae Sunflower 
Dyssodia concinna (Gray) Rob. [Thymophylla concinna (Gray) Strother]. f=Compositae Sunflower 
Dyssodia pentachaeta (DC.) Rob. [Thymophylla pentachaeta (DC.) Small]. f=Compositae Sunflower 
Dyssodia porophylloides Gray. [Adenophyllum porophylloides (Gray) f=Compositae Sunflower 
Echinocereus fasciculatus (Engelm.) Benson. [E. fendleri Engelm. var. f=Cactaceae Cactus 
Echinocereus triglochidiatus Engelm. Claret cup. Local stem succulent; f=Cactaceae Cactus 
Echinochloa colonum (L.) Link. Jungle ricegrass. Scattered exotic f=Gramineae Grass 
Echinopepon wrightii (Gray) Wats. Wild balsam apple. Local annual f=Cucurbitaceae Gourd 
Elymus elymoides (Raf.) Swezey. [Sitanion hystrix (Nutt.) J. G. Smith]. f=Gramineae Grass 
Encelia farinosa Gray. var. farinosa. Brittlebush, incienso. Widespread f=Compositae Sunflower 
Encelia frutescens Gray. Green brittlebush. Local subshrub; rare on f=Compositae Sunflower 
Enneapogon cenchroides (Roem. &amp; Schult.) C. E. Hubb. [E. mollis f=Gramineae Grass 
Enneapogon desvauxii Beauv. Spike pappusgrass. Widespread perennial; f=Gramineae Grass 
Eragrostis barrelieri Daveau. Mediterranean lovegrass. Local exotic f=Gramineae Grass 
Eragrostis cilianensis (All.) Vign. &amp; Lutati ex Janchen. Stink f=Gramineae Grass 
Eragrostis curvula (Schrad.) Nees var. conferta Nees. [Eragrostis chloromelas f=Gramineae Grass 
Eragrostis echinochloidea Stapf. Lovegrass. Scattered exotic perennial; f=Gramineae Grass 
Eragrostis intermedia A. S. Hitchc. Plains lovegrass. Local perennial; f=Gramineae Grass 
Eragrostis lehmanniana Nees. Lehmann lovegrass. Widespread exotic f=Gramineae Grass 
Eragrostis pectinacea (Michx.) Nees. Lovegrass. Local annual; mesas, f=Gramineae Grass 
Eremalche exilis (Gray) Greene. [Malvastrum exile Gray]. Local annual; f=Malvaceae Mallow 
Eriastrum diffusum (Gray) Mason. Widespread annual; common (abundant f=Polemoniaceae Phlox 
Ericameria cuneata (Gray) McClatchie. [Haplopappus cuneatus Gray]. f=Compositae Sunflower 
Ericameria laricifolia (Gray) Shinners. [Haplopappus laricifolius f=Compositae Sunflower 
Erigeron colomexicanus A. Nels. Fleebane daisy. Local annual, uncommon f=Compositae Sunflower 
Erigeron divergens T. &amp; G. Fleabane daisy. Scattered annual; uncommon f=Compositae Sunflower 
Erigeron lobatus A. Nels. Fleabane daisy. Local annual; uncommon on f=Compositae Sunflower 
Eriochloa acuminata (Presl.) Kunth. [E. gracilis (Fourn.) Hitchc., f=Gramineae Grass 
Eriogonum abertianum Torr. Wild buckwheat. Widespread annual; very f=Polygonaceae Buckwheat 
Eriogonum deflexum Torr. Skeleton weed. Widespread annual; common f=Polygonaceae Buckwheat 
Eriogonum inflatum Torr. &amp; Frem. Desert trumpet, cigaret plant. f=Polygonaceae Buckwheat 
Eriogonum maculatum Heller. Anglestem buckwheat, spotted buckwheat. f=Polygonaceae Buckwheat 
Eriogonum palmerianum Reveal. [E. densum sensu K. &amp; P.]. Skeleton f=Polygonaceae Buckwheat 
Eriogonum polycladon Benth. Sorrel buckwheat. Local annual; very common f=Polygonaceae Buckwheat 
Eriogonum reniforme Torr. &amp; Frem. Kidneyleaf buckwheat. Local f=Polygonaceae Buckwheat 
Eriogonum thurberi Torr. Thurber buckwheat. Local annual; uncommon f=Polygonaceae Buckwheat 
Eriogonum trichopes Torr. Little trumpet. Local annual; common (abundant f=Polygonaceae Buckwheat 
Eriogonum wrightii Torr. var. wrightii. Wild buckwheat. Widespread f=Polygonaceae Buckwheat 
Erioneuron pulchellum (H.B.K.) Tateoka. [Tridens pulchellus (H.B.K.) f=Gramineae Grass 
Eriophyllum lanosum Gray. Wooly eriophyllum. Scattered annual; common f=Compositae Sunflower 
Erodium cicutarium (L.) L'Her. Filaree. Widespread exotic annual; f=Geraniaceae Geranium 
Erodium texanum Gray. Largeflower stork's bill. Widespread annual; f=Geraniaceae Geranium 
Eschscholtzia mexicana Greene. Mexican gold poppy. Widespread annual; f=Papaveraceae Poppy 
Eucrypta chrysanthemifolia (Benth.) Greene. Torrey eucrypta. Widespread f=Hydrophyllaceae Water leaf 
Eucrypta micrantha (Torr.) Heller. Smallflower eucrypta. Widespread f=Hydrophyllaceae Water leaf 
Eupatorium solidaginifolium Gray. Boneset. Widespread herbaceous perennial; f=Compositae Sunflower 
Evax multicaulis DC. Rabbit tobacco. Local annual; rare, Tumamoc Hill; f=Compositae Sunflower 
Evolvulus alsinoides L. Arizona blue eyes, dio de vibora. Widespread f=Convolvulaceae Morning Glory 
Evolvulus nuttallianus Roemer &amp; Schultes. [Evolvulus pilosus Nutt.]. f=Convolvulaceae Morning Glory 
Ferocactus cylindraceus Orcutt. [Ferocactus acanthodes (Lemaire) Britt. f=Cactaceae Cactus 
Ferocactus cylindraceus Orcutt. x F. wislizenii (Engelm.) Britt. &amp; f=Cactaceae Cactus 
Ferocactus wislizenii (Engelm.) Britt. &amp; Rose. Fishhook barrel f=Cactaceae Cactus 
Filago arizonica Gray. Arizona filago. Local annual; rare (common f=Compositae Sunflower 
Filago californica Nutt. California filago. Scattered annual; rare f=Compositae Sunflower 
Filago depressa Gray. Dwarf filago. Local annual; rare (common in f=Compositae Sunflower 
Forestiera shrevei Standl. [F. phillyreoides (Benth.) Torr.]. Desert f=Oleaceae Olive 
Gaillardia arizonica Gray. Blanket flower. Local annual; rare, Tumamoc f=Compositae Sunflower 
Gaillardia pulchella Foug. Blanket flower. Local annual; rare, Anklam f=Compositae Sunflower 
Galactia wrightii Gray. Local herbaceous perennial; abundant on rocky f=Leguminosae Pea 
Galium aparine L. Bedstraw. Widespread exotic annual; common on rocky f=Rubiaceae Madder 
Galium proliferum Gray. Bedstraw. Widespread annual; common on rocky f=Rubiaceae Madder 
Galium stellatum Kell. var. eremicum Hilend &amp; Howell. Bedstraw. f=Rubiaceae Madder 
Gaura parviflora Dougl. Lizard tail. Local annual or biennial; common f=Onagraceae Evening Primrose 
Gilia capitata Sims. Local annual; 12 miles northwest of Tucson, Tucson f=Polemoniaceae Phlox 
Gilia flavocincta A. Nels. ssp. australis (A. &amp; V. Grant) Day f=Polemoniaceae Phlox 
Gilia stellata Heller. Widespread annual; common on rocky slopes, f=Polemoniaceae Phlox 
Gnaphalium leucocephalum Gray. White cudweed, gordolobo. Local herbaceous f=Compositae Sunflower 
Gnaphalium purpureum L. Purple cudweed. Local annual or perennial herb; f=Compositae Sunflower 
Gnaphalium wrightii Gray. Gordolobo, everlasting. Local herbaceous f=Compositae Sunflower 
Gomphrena sonorae  f=Amaranthaceae Amaranth 
Gutierrezia arizonica (Gray) Lane. [Greenella arizonica Gray]. Scattered f=Compositae Sunflower 
Gutierrezia microcephala (DC.) Gray. [incl. G. linioides Greene, G. f=Compositae Sunflower 
Gymnosperma glutinosum (Spreng.) Less. [Selloa glutinosa Spreng.]. f=Compositae Sunflower 
Haplophyton crooksii f=Apocynaceae Dogbane 
Harpagonella palmeri Gray. Widespread annual; uncommon to common on f=Boraginaceae Borage 
Hedeoma nanum (Torr.) Briq. Mock pennyroyal. Local annual or perennial f=Labiatae Mint 
Helianthus annuus L. Sunflower. Local annual; common along edge of f=Compositae Sunflower 
Helianthus petiolaris Nutt. Sunflower. Local annual; rare on Kinney f=Compositae Sunflower 
Hemizonia kelloggii Greene. Tarweed. Local exotic annual; common weed f=Compositae Sunflower 
Herissantia crispa (L.) Brizicky. [Gayoides crispum (L.) Small]. Widespread f=Malvaceae Mallow 
Hermannia pauciflora Wats. Hierba del soldado. Local herbaceous perennial; f=Sterculiaceae Cacao 
Herniaria cinerea DC. Burstwort. Local exotic annual; flats northwest f=Caryophyllaceae Pink 
Heteropogon contortus (L.) Beauv. Tanglehead. Widespread perennial; f=Gramineae Grass 
Heterotheca psammophila Wagenkn. [H. subaxillaris (Lam.) Britt. &amp; f=Compositae Sunflower 
Hibiscus biseptus Wats. Sonoran rose mallow. Local herbaceous perennial; f=Malvaceae Mallow 
Hibiscus coulteri Harv. Desert rose mallow. Widespread subshrub; common f=Malvaceae Mallow 
Hibiscus denudatus Benth. Rock rose mallow. Widespread subshrub; common f=Malvaceae Mallow 
Hilaria belangeri (Steud.) Nash. Curly mesquite grass. Widespread f=Gramineae Grass 
Hilaria mutica (Buckl.) Benth. Tobosa. Scattered perennial; uncommon f=Gramineae Grass 
Hoffmanseggia glauca (Ort.) Eifeort. [H. densiflora Benth.]. Hog potato. f=Leguminosae Pea 
Hordeum murinum L. ssp. glaucum (Steud.) Tzvel. [H. leporinum Link]. f=Gramineae Grass 
Hordeum pusillum Nutt. Little barley. Local annual; common on disturbed f=Gramineae Grass 
Horsfordia newberryi (Wats.) Gray. Yellow felt plant. Local shrub; f=Malvaceae Mallow 
Hybanthus verticillatus (Ort.) Baill. Green violet. Local herbaceous f=Violaceae Violet 
Hymenoclea salsola T. &amp; G. var. pentalepis (Rydb.) L. Benson. f=Compositae Sunflower 
Hymenothrix wislizenii Gray. Widespread annual; common on roadsides f=Compositae Sunflower 
Hyptis emoryi Torr. Desert lavender. Widespread shrub; uncommon on f=Labiatae Mint 
Ipomoea barbatisepala Gray. Morning glory. Scattered annual vine climbing f=Convolvulaceae Morning Glory 
Ipomoea costellata Torr. Morning glory. Local annual vine; rare on f=Convolvulaceae Morning Glory 
Ipomoea cristulata Hallier f. [Ipomoea coccinea L.]. Scarlet creeper. f=Convolvulaceae Morning Glory 
Ipomoea hederacea (L.) Jacq. [Ipomoea hirsutula Jacq. f., in part]. f=Convolvulaceae Morning Glory 
Ipomopsis longiflora (Torr.) V. Grant. [Gilia longiflora (Torr.) G. f=Polemoniaceae Phlox 
Isocoma tenuisecta Greene. [Haplopappus tenuisectus (Greene) Blake]. f=Compositae Sunflower 
Iva ambrosiaefolia Gray. Scattered annual; uncommon along sandy washes f=Compositae Sunflower 
Janusia gracilis Gray. Desert vine. Widespread woody vine (somestimes f=Malpighiaceae Malpighia 
Justicia californica f=Acanthaceae Acanthus 
Kallstroemia californica (Wats.) Vail. Little summer poppy, California f=Zygophyllaceae Caltrop 
Kallstroemia grandiflora Torr. Arizona poppy, summer poppy, orange f=Zygophyllaceae Caltrop 
Kallstroemia parviflora Norton. Local annual; rare along King Canyon; f=Zygophyllaceae Caltrop 
Koeberlinia spinosa Zucc. Allthorn. Scattered shrub; uncommon to common f=Capparidaceae Caper 
Krameria erecta Willd. [K. parvifolia Benth.]. Range ratany. Widespread f=Krameriaceae Ratany 
Krameria grayi Rose &amp; Paintermediate. White ratany. Widespread f=Krameriaceae Ratany 
Lactuca serriola L. Prickly lettuce. Local exotic annual; rare on gravelly f=Compositae Sunflower 
Lamarckia aurea (L.) Moench. Goldentop. Local exotic annual; mesas, f=Gramineae Grass 
Lamium amplexicaule L. Henbit. Local exotic annual; rare, near buildings, f=Labiatae Mint 
Lantana camara L. Lantana. Local exotic shrub; uncommon on disturbed f=Verbenaceae Vervain 
Lappula redowskii (Hornem.) Greene. Stickseed. Scattered annual; common f=Boraginaceae Borage 
Lappula texana (Scheele) Britt. Stickseed. Local annual; very common f=Boraginaceae Borage 
Larrea divaricata Cav. ssp. tridentata (DC.) Felger &amp; Lowe. [L. f=Zygophyllaceae Caltrop 
Lasthenia californica DC. [Baeria chrysostoma F. &amp; M.]. Goldfields. f=Compositae Sunflower 
Layia glandulosa (Hook.) H. &amp; A. Tiddy tips. Local annual; Gates f=Compositae Sunflower 
Lepidium lasiocarpum Nutt. Sand peppergrass. Widespread annual; very f=Cruciferae Mustard 
Lepidium medium Greene. Peppergrass. Scattered annual; common (abundant f=Cruciferae Mustard 
Lepidium thurberi Wooton. Peppergrass. Local perennial?; rare along f=Cruciferae Mustard 
Leptochloa dubia (H.B.K.) Nees. Green sprangletop. Scattered perennial; f=Gramineae Grass 
Leptochloa fascicularis (Lam.) Gray. Beaded sprangletop. Local annual; f=Gramineae Grass 
Leptochloa filiformis (Lam.) Beauv. Red sprangletop. Widespread annual; f=Gramineae Grass 
Leptochloa uninervia (Presl.) A. S. Hitchc. Mexican sprangletop. Local f=Gramineae Grass 
Lesquerella gordonii (Gray) Wats. Gordon bladderpod. Widespread annual; f=Cruciferae Mustard 
Lesquerella purpurea (Gray) Wats. White bladderpod. Widespread herbaceous f=Cruciferae Mustard 
Leucelene ericoides (Torr.) Greene. [Aster hirtifolius Blake, A. arenosus f=Compositae Sunflower 
Linanthus aureus (Nutt.) Greene. Local annual; mesas, Tucson (Mrs. f=Polemoniaceae Phlox 
Linanthus bigelovii (Gray) Greene. Scattered annual; uncommon (common f=Polemoniaceae Phlox 
Linaria texana Scheele. Texas toad flax. Local annual; rare on rocky f=Scrophulariaceae Figwort 
Linum grandiflorum Desf. Flax. Local exotic annual?; rare on northside f=Linaceae Flax 
Linum lewisii Pursh. Blue flax. Local annual or perennial; rare on f=Linaceae Flax 
Linum puberulum (Engelm.) Heller. Local annual; single plant on flats f=Linaceae Flax 
Loeflingia squarrosa Nutt. Local annual; rare, just west of ASDM, f=Caryophyllaceae Pink 
Lomatium nevadense (Wats.) Coult.&amp; Rose var. nevadense. Wild parsley. f=Umbelliferae Parsley 
Lotus greenei (Woot. &amp; Standl.) Ottley. Deer vetch. Local herbaceous f=Leguminosae Pea 
Lotus humistratus Greene. Hill locust. Scattered annual; common on f=Leguminosae Pea 
Lotus rigidus (Benth.) Greene. Desert rock pea. Local herbaceous perennial; f=Leguminosae Pea 
Lotus salsuginosus Greene. var. brevivexillus Ottley. [L. humilis Greene]. f=Leguminosae Pea 
Lotus strigosus (Nutt.) Greene var. tomentellus (Greene) Isely. [Lotus f=Leguminosae Pea 
Lupinus concinnus Agardh. Elegant lupine. Local (scattered in 1992) f=Leguminosae Pea 
Lupinus sparsiflorus Benth. Arizona lupine. Widespread annual; very f=Leguminosae Pea 
Lycium andersonii Gray. Narrowleaf wolfberry. Local shrub; rare on f=Solanaceae Potato, Nightshade 
Lycium andersonii Gray x L. fremontii Gray. Hybrid wolfberry. Local f=Solanaceae Potato, Nightshade 
Lycium berlandieri Dunal. var. longistylum (L.) Hitch. Berlandier f=Solanaceae Potato, Nightshade 
Lycium exsertum Gray. Wolfberry. Local shrub; rare Rattlesnake Pass f=Solanaceae Potato, Nightshade 
Lycium fremontii Gray. Fremont wolfberry. Local shrub; uncommon on f=Solanaceae Potato, Nightshade 
Lycium macrodon Gray. Peachthorn. Local shrub; Rattlesnake Pass (L. f=Solanaceae Potato, Nightshade 
Lycurus setosus (Nutt.) C. G. Reeder. [L. phleoides H.B.K. var. glaucifolius f=Gramineae Grass 
Machaeranthera asteroides (Torr.) Greene var. asteroides. [Aster tephrodes f=Compositae Sunflower 
Machaeranthera gracilis (Nutt.) Shinners. [Haplopappus gracilis (Nutt.) f=Compositae Sunflower 
Machaeranthera pinnatifida (Hook.) Shinners var. pinnatifida. [Haplopappus f=Compositae Sunflower 
Machaeranthera tagetina Greene. [Aster tagetinus (Greene) Blake]. f=Compositae Sunflower 
Malacothrix californica DC. var. glabrata Gray ex DC. Eaton. [M. glabrata f=Compositae Sunflower 
Malacothrix clevelandii Gray. [M. sonorae Davis &amp; Raven]. Yellow f=Compositae Sunflower 
Malacothrix coulteri Gray. Snakes head. Local annual; Tucson Mts. f=Compositae Sunflower 
Malacothrix fendleri Gray. Local annual; rare on steep rocky slopes f=Compositae Sunflower 
Malva parviflora L. Little mallow. Scattered exotic annual or biennial; f=Malvaceae Mallow 
Malvastrum bicuspidatum (Wats.) Rose. Malva peluda, Tachi. Local subshrub; f=Malvaceae Mallow 
Mammillaria grahamii Engelm. [M. microcarpa Engelm.]. Fishhook pincushion. f=Cactaceae Cactus 
Mammillaria thornberi Orcutt. Thornber pincushion. Local stem succulent; f=Cactaceae Cactus 
Mammillaria viridiflora (Britt. &amp; Rose.) Bodeker. Fishhook pincushion. f=Cactaceae Cactus 
Margaranthus solanaceus Schlecht. Netted globeberry. Local annual; f=Solanaceae Potato, Nightshade 
Marina parryi (T. &amp; G.) Barneby. [Dalea parryi T. &amp; G.]. Parry f=Leguminosae Pea 
Matelea parvifolia (Torr.) Woods. [Gonolobus parvifolius Torr.]. Milkweed f=Asclepiadaceae Milkweed 
Matelea producta Woodson. [Gonolobus productus Torr.]. Local woody f=Asclepiadaceae Milkweed 
Matricaria matricarioides (Less.) Porter. Pineapple weed. Local exotic f=Compositae Sunflower 
Matthiola longipetala (Vent.) DC. var. bicornis Sibth. &amp; Smith. f=Cruciferae Mustard 
Maurandya antirrhiniflora H. &amp; B. Snapdragon vine. Scattered herbaceous f=Scrophulariaceae Figwort 
Medicago polymorpha L. var. vulgaris (Benth.) Shinners. [M. hispida f=Leguminosae Pea 
Medicago sativa L. Alfalfa. Local exotic herbaceous perennial; uncommon f=Leguminosae Pea 
Melia azedarach L. Chinaberry. Local exotic tree; rare, in gravel floodplain f=Meliaceae Melia 
Melilotus indicus (L.) All. Alfalfilla. Local exotic annual; uncommon f=Leguminosae Pea 
Menodora scabra Gray. Twinberry. Widespread subshrub; very common f=Oleaceae Olive 
Mentzelia affinis Greene. Blazing star, stickleaf. Widespread annual; f=Loasaceae Stickleaf 
Mentzelia albicaulis Dougl. Smallflower blazing star. Local annual; f=Loasaceae Stickleaf 
Mentzelia jonesii (U. &amp; G.) Thompson &amp; Roberts. [M. nitens f=Loasaceae Stickleaf 
Mentzelia multiflora (Nutt.) Gray. ssp. multiflora. [M. pumila (Nutt.) f=Loasaceae Stickleaf 
Mentzelia texana Urb. &amp; Gilb. [M. asperula Woot. &amp; Standl.]. f=Loasaceae Stickleaf 
Merremia dissecta (Jacq.) H. G. Hallier. Mile &amp; a &amp; minute f=Convolvulaceae Morning Glory 
Microseris linearifolia (DC.) Schultz Bip. Silver puffs. Widespread f=Compositae Sunflower 
Mimosa aculeaticarpa Ortega var. biuncifera (Benth.) Barneby. [M. f=Leguminosae Pea 
Mimosa distachya Brandegee var. laxiflora (Benth.) Barneby. [M. laxiflora f=Leguminosae Pea 
Mimulus guttatus DC. Monkey flower. Scattered herbaceous perennial; f=Scrophulariaceae Figwort 
Mimulus nasutus Greene. Monkey flower. Local annual; rare in moist f=Scrophulariaceae Figwort 
Mimulus rubellus Gray. Red &amp; stemmed Mimulus. Local annual; common f=Scrophulariaceae Figwort 
Mirabilis bigelovii Gray. Wishbone bush. Widespread herbaceous perennial, f=Nyctaginaceae Four o'clock 
Mirabilis multiflora (Torr.) Gray. Colorado four o'clock. Local herbaceous f=Nyctaginaceae Four o'clock 
Mollugo cerviana (L.) Seringe. Threadstem carpet weed. Local annual; f=Molluginaceae Mollugo 
Mollugo verticillata L. Indian chick weed. Local annual; rare, Oeste f=Molluginaceae Mollugo 
Molucella laevis L. Shell flower, bells of Ireland. Local exotic annual; f=Labiatae Mint 
Monolepis nuttalliana (Schult.) Greene. Poverty weed. Local annual; f=Chenopodiaceae Goosefoot 
Monoptilon bellioides (Gray) H.M. Hall. Desert star. Scattered annual; f=Compositae Sunflower 
Morus microphylla Buckl. Texas mulberry. Local shrub; single shrub f=Moraceae Mulberry 
Muhlenbergia emersleyi Vasey. Bull grass. Local perennial; common f=Gramineae Grass 
Muhlenbergia microsperma (DC.) Kunth. Littleseed muhly. Scattered f=Gramineae Grass 
Muhlenbergia monticola Buckl. Mesa muhly. Local perennial/annual; f=Gramineae Grass 
Muhlenbergia porteri Scribn. Bush muhly. Widespread perennial; very f=Gramineae Grass 
Muhlenbergia rigens (Benth.) A. S. Hitchc. Deer grass. Local perennial; f=Gramineae Grass 
Myosurus cupulatus Wats. Mousetail. Local annual; abundant on rocky f=Ranunculaceae Crowfoot 
Nama demissum Gray. Purple mat. Local annual; common in washes, Ez f=Hydrophyllaceae Water leaf 
Nama hispidum Gray. Sand bells. Local annual; uncommon on flats, bajadas, f=Hydrophyllaceae Water leaf 
Nemacladus glanduliferus Jeps. Thread plant. Scattered (widespread f=Campanulaceae Bellflower 
Nicotiana glauca Graham. Tree tobacco. Local exotic shrub; rare along f=Solanaceae Potato, Nightshade 
Nicotiana trigonophylla Dunal. Desert tobacco. Widespread herbaceous f=Solanaceae Potato, Nightshade 
Nissolia schottii (Torr.) Gray. Widespread woody vine, climbing on f=Leguminosae Pea 
Notholaena cochisensis  f=Adiantaceae Fern 
Notholaena sinuata  f=Adiantaceae Fern 
Notholaena standleyi  f=Adiantaceae Fern 
Oenothera caespitosa Nutt. Large white desert primrose. Local herbaceous f=Onagraceae Evening Primrose 
Oenothera primiveris Gray. Yellow desert primrose. Widespread annual; f=Onagraceae Evening Primrose 
Oligomeris linifolia (Vahl) Macbr. Linearleaf cambess. Scattered annual; f=Resedaceae Mignonette 
Olneya tesota Gray. Ironwood. Widespread tree; very common on rocky f=Leguminosae Pea 
Opuntia acanthocarpa Engelm. &amp; Bigel. var. major (Engelm. &amp; f=Cactaceae Cactus 
Opuntia acanthocarpa Engelm. &amp; Bigel. x O. spinosior (Engelm.) f=Cactaceae Cactus 
Opuntia acanthocarpa Engelm. &amp; Bigel. x O. versicolor Engelm. Hybrid f=Cactaceae Cactus 
Opuntia arbuscula Engelm. Pencil cholla. Local stem succulent; very f=Cactaceae Cactus 
Opuntia bigelovii Engelm. Teddy bear cholla. Scattered stem succulent; f=Cactaceae Cactus 
Opuntia chlorotica Engelm. &amp; Bigel. Pancake prickly pear. Scattered f=Cactaceae Cactus 
Opuntia fulgida Engelm. var. fulgida. Chainfruit cholla. Widespread f=Cactaceae Cactus 
Opuntia fulgida Engelm. var. mammillata (Schott) Coult. Local stem f=Cactaceae Cactus 
Opuntia imbricata Haw. x O. versicolor Engelm. Hybrid Cholla. Local f=Cactaceae Cactus 
Opuntia leptocaulis DC. Christmas cactus. Widespread stem succulent; f=Cactaceae Cactus 
Opuntia leptocaulis DC. x O. spinosior (Engelm.) Toumey. Hybrid pencil f=Cactaceae Cactus 
Opuntia lindheimeri Engelm. var. linguiformis (Griffiths) L. Benson. f=Cactaceae Cactus 
Opuntia microdasys (Lehm.) Pfeifl. Bunny ears, nopal cegador. Local f=Cactaceae Cactus 
Opuntia phaeacantha Engelm. var. major Engelm. Sprawling prickly pear. f=Cactaceae Cactus 
Opuntia phaeacantha var. discata (Griffiths) Benson &amp; Walkington. f=Cactaceae Cactus 
Opuntia santa-rita (Griffiths &amp; Hare) Rose. [O. violacea Engelm. f=Cactaceae Cactus 
Opuntia spinosior (Engelm.) Toumey. Cane cholla. Scattered stem succulent; f=Cactaceae Cactus 
Opuntia spinosior (Engelm.) Toumey x O. versicolor Engelm. Hybrid cholla. f=Cactaceae Cactus 
Opuntia versicolor Engelm. Staghorn cholla. Widespread stem succulent; f=Cactaceae Cactus 
Opuntia vivipara Rose. Hybrid Cholla. Local stem succulent very common f=Cactaceae Cactus 
Opuntia x kelvinensis Grant &amp; Grant. [Opuntia fulgida Engelm. f=Cactaceae Cactus 
Opuntia x tetracantha Toumey. [O. kleiniae DC. var. tetracantha (Toumey) f=Cactaceae Cactus 
Orobanche ludoviciana Nutt. var. cooperi (Gray) G. Beck. [O. cooperi f=Orobanchaceae Broom Rape 
Orthocarpus purpurascens Benth. Owl clover. Local annual; uncommon f=Scrophulariaceae Figwort 
Oxybaphus coccineus Torr. [Mirabilis coccineus (Torr.) B. &amp; H.]. f=Nyctaginaceae Four o'clock 
Panicum hirticaule Presl. [P. capillare L. var. hirticaule (Presl.) f=Gramineae Grass 
Panicum miliaceum L. Broomcorn millet. Local exotic annual; uncommon f=Gramineae Grass 
Panicum obtusum H.B.K. Vine mesquite. Local perennial; common along f=Gramineae Grass 
Pappophorum vaginatum Buckl. [P. mucronulatum Nees.]. Pappus grass. f=Gramineae Grass 
Parietaria hespera B. D. Hinton. var. hespera. [P. floridana Nutt. f=Urticaceae Nettle 
Parietaria pennsylvanica Muhl. Hammerwort. Local annual; rare under f=Urticaceae Nettle 
Parkinsonia aculeata L. Mexican paloverde. Scattered tree; rare on f=Leguminosae Pea 
Parthenium incanum H.B.K. Mariola. Widespread subshrub; abundant on f=Compositae Sunflower 
Pectis cylindrica (Fern.) Rydb. Local annual; rare, Picture Rocks Retreat f=Compositae Sunflower 
Pectis filipes Harv. &amp; Gray. Local annual; rare on rocky slopes f=Compositae Sunflower 
Pectis linifolia L. Local annual; rare on steep rocky slopes in desertscrub f=Compositae Sunflower 
Pectis papposa Harv. &amp; Gray. Chinchweed. Widespread annual; common f=Compositae Sunflower 
Pectocarya heterocarpa Johnst. Hairy &amp; leaved combbur. Scattered f=Boraginaceae Borage 
Pectocarya platycarpa Munz &amp; Johnst. Broadnut combbur. Scattered f=Boraginaceae Borage 
Pectocarya recurvata Johnst. Archnut combbur. Widespread annual; very f=Boraginaceae Borage 
Pellaea truncata  f=Adiantaceae Fern 
Pellaea wrightiana f=Adiantaceae Fern 
Peniocereus greggii (Engelm.) Britt. &amp; Rose. [Cereus greggii Engelm.]. f=Cactaceae Cactus 
Pennisetum ciliare (L.) Link. Buffel grass. Scattered exotic perennial; f=Gramineae Grass 
Pennisetum setaceum (Forsk.) Chiov. Fountain grass. Scattered exotic f=Gramineae Grass 
Penstemon parryi Gray. Parry beard tongue. Widespread herbaceous perennial; f=Scrophulariaceae Figwort 
Penstemon subulatus Jones. Little beardtongue. Local herbaceous perennial; f=Scrophulariaceae Figwort 
Perityle emoryi Torr. Rock daisy. Local annual; rare on steep rocky f=Compositae Sunflower 
Perityle lemmonii (Gray) Macbride. [Laphamia dissecta Torr.]. Rock f=Compositae Sunflower 
Petunia parviflora Juss. Wild petunia. Local annual; uncommon in moist f=Solanaceae Potato, Nightshade 
Phacelia affinis Gray. Purple bell phacelia, caterpillar weed. Local f=Hydrophyllaceae Water leaf 
Phacelia bombycina Woot. &amp; Standl. [Phacelia crenulata Torr. sensu f=Hydrophyllaceae Water leaf 
Phacelia campanularia Gray. Desert Canterbury bells. Local exotic annual; f=Hydrophyllaceae Water leaf 
Phacelia coerulea Greene. Caterpillar weed. Scattered annual; common f=Hydrophyllaceae Water leaf 
Phacelia distans Benth. Caterpillar weed. Widespread annual; very f=Hydrophyllaceae Water leaf 
Phacelia popei Torr. &amp; Gray var. arizonica (Gray) Voss [P. arizonica f=Hydrophyllaceae Water leaf 
Phalaris minor Retz. Littleseed canary grass. Local exotic annual; f=Gramineae Grass 
Phaseolus acutifolius Gray var. latifolius Freeman. Tepary bean. Local f=Leguminosae Pea 
Phaseolus acutifolius Gray. var. tenuifolius Gray. Wild bean. Local f=Leguminosae Pea 
Phaseolus filiformis Benth. [P. wrightii Gray]. Local herbaceous annual f=Leguminosae Pea 
Phlox tenuifolia E. Nels. Scattered herbaceous perennial; common on f=Polemoniaceae Phlox 
Pholistoma auritum (Lindl.) Lilja. Widespread annual; common under f=Hydrophyllaceae Water leaf 
Phoradendron californicum Nutt. Desert mistletoe. Widespread perennial f=Viscaceae Mistletoe 
Phragmites australis (Cav.) Trin. ex Steud. [P. communis Trin.]. Common f=Gramineae Grass 
Physalis acutifolia (Miers) Sandw. [Physalis wrightii Gray]. Sharpleaf f=Solanaceae Potato, Nightshade 
Physalis crassifolia Benth. Thickleaf ground cherry. Scattered herbaceous f=Solanaceae Potato, Nightshade 
Physalis lobata Torr. [Quincula lobata (Torr.) Raf.]. Purple ground f=Solanaceae Potato, Nightshade 
Plagiobothrys arizonicus (Gray) Greene. Blood weed. Scattered annual; f=Boraginaceae Borage 
Plagiobothrys pringlei Greene. Popcorn flower. Local annual; common f=Boraginaceae Borage 
Plantago bigelovii Gray. [P. heterophylla Nutt. ssp. californica (Greene) f=Plantaginaceae Plantain 
Plantago fastigiata Morris. [P. insularis Eastw. sensu K. &amp; P.]. f=Plantaginaceae Plantain 
Plantago patagonica Jacq. [P. purshii R. &amp; S.]. Pursh plantain. f=Plantaginaceae Plantain 
Plantago rhodosperma Decne. Redseed plantain. Local annual; common f=Plantaginaceae Plantain 
Plumbago scandens L. Hierba de alacrán. Local herbaceous perennial; f=Plumbaginaceae Plumbago 
Poa bigelovii Vasey &amp; Scribn. Bigelow's bluegrass. Widespread f=Gramineae Grass 
Polanisia dodecandra (L.) DC. ssp. trachysperma (T. &amp; G.) Iltis. f=Capparidaceae Caper 
Polygala macradenia Gray. Milkwort. Scattered subshrub; common on f=Polygalaceae Milkwort 
Polypogon monspeliensis (L.) Desf. Rabbitfoot grass. Local exotic f=Gramineae Grass 
Populus fremontii Wats. Fremont cottonwood. Local tree; rare along f=Salicaceae Willow 
Porophyllum gracile Benth. Odora. Widespread herbaceous perennial; f=Compositae Sunflower 
Portulaca oleracea L. [incl. P. retusa Engelm.]. Common purslane, verdolaga. f=Portulacaceae Portulaca 
Portulaca suffrutescens Engelm. Scattered herbaceous perennial; uncommon f=Portulacaceae Portulaca 
Portulaca umbraticola H.B.K. [P. coronata Small]. Scattered annual; f=Portulacaceae Portulaca 
Prenanthella exigua (Gray) Rydb. [Lygodesmia exigua Gray]. Local annual; f=Compositae Sunflower 
Proboscidea altheaefolia (Benth.) Decne. [incl. P. arenaria (Engelm.) f=Pedaliaceae Unicorn Plant 
Proboscidea parviflora (Woot.) Woot. &amp; Standl. Devil's claw. Local f=Pedaliaceae Unicorn Plant 
Prosopis velutina Woot. Velvet mesquite. Widespread tree; abundant f=Leguminosae Pea 
Psilostrophe cooperi (Gray) Greene. Paper flower. Widespread herbaceous f=Compositae Sunflower 
Rafinesquia californica Nutt. California chicory. Local annual; rare f=Compositae Sunflower 
Rafinesquia neomexicana Gray. Desert dandelion. Widespread annual; f=Compositae Sunflower 
Rhus aromatica Ait. var. pilosissima  f=Anacardiaceae Cashew , Sumac Family
Rhus lancea  f=Anacardiaceae Cashew , Sumac Family
Rhynchelytrum repens (Willd.) C.E. Hubb. [R. roseum Nees]. Natal grass. f=Gramineae Grass 
Rhynchosia senna Gill. [R. texana T. &amp; G.]. Rosary bean. Local f=Leguminosae Pea 
Ruellia nudiflora f=Acanthaceae Acanthus 
Salsola australis R. Br. [S. iberica Sennen &amp; Pau, S. kali L. f=Chenopodiaceae Goosefoot 
Salvia columbariae Benth. Chia. Widespread annual; common in wet springs f=Labiatae Mint 
Salvia pinguifolia (Fern.) Woot. &amp; Standl. Rock sage. Local shrub; f=Labiatae Mint 
Sambucus mexicana Presl. Mexican elder. Local shrub; rare on septic f=Caprifoliaceae Honeysuckle 
Sanvitalia abertii Gray. Local annual; common in sand along small wash, f=Compositae Sunflower 
Sarcostemma cynanchoides Decne. ssp. cynanchoides. [Funastrum cynanchoides f=Asclepiadaceae Milkweed 
Sarcostemma cynanchoides Decne. ssp. hartwegii (Vail) Holm. [Funastrum f=Asclepiadaceae Milkweed 
Schismus barbatus (L.) Thell. [incl. S. arabicus Nees]. Mediterranean f=Gramineae Grass 
Scirpus maritimus L. var. paludosus (A. Nels.) Koyama. [S. paludosus f=Cyperaceae Sedge 
Scleropogon brevifolius Phil. Burro grass. Local perennial; common f=Gramineae Grass 
Selaginella arizonica Maxon. Spike moss. Widespread herbaceous perennial; f=Selaginellaceae Selaginella 
Senecio douglasii DC. var. monoensis (Greene) Jepson. [S. monoensis f=Compositae Sunflower 
Senecio lemmonii Gray. Groundsel. Widespread herbaceous perennial; f=Compositae Sunflower 
Senna bauhinioides (Gray) Irwin &amp; Barneby. [Cassia bauhinioides f=Leguminosae Pea 
Senna covesii (Gray) Irwin &amp; Barneby. [Cassia covesii Gray]. Desert f=Leguminosae Pea 
Setaria adhaerans (Forssk.) Chiov. Bur bristlegrass. Local exotic perennial; f=Gramineae Grass 
Setaria arizonica Roem. Local annual; 10 miles west of Tucson on San f=Gramineae Grass 
Setaria grisebachii Fourn. Grisebach bristlegrass. Local annual; common f=Gramineae Grass 
Setaria leucopila (Scribn. &amp; Merr.) K. Schum. [S. macrostachya f=Gramineae Grass 
Setaria liebmannii Fourn. Bristlegrass. Scattered annual; uncommon f=Gramineae Grass 
Setaria macrostachya H.B.K. Plains bristlegrass. Scattered perennial; f=Gramineae Grass 
Sida abutifolia Miller. [S. filicaulis T. &amp; G., S. procumbens f=Malvaceae Mallow 
Sida physocalyx Gray. [Rhynchosida physocalyx (Gray) Fryxell]. Tuberous f=Malvaceae Mallow 
Silene antirrhina L. Sleepy catchfly. Widespread annual; uncommon f=Caryophyllaceae Pink 
Simmondsia chinensis (Link) Schneid. Jojoba. Widespread shrub; very f=Simmondsiaceae Jojoba 
Siphonoglossa longiflora f=Acanthaceae Acanthus 
Sisymbrium irio L. London rocket. Widespread exotic annual; common f=Cruciferae Mustard 
Sisymbrium orientale L. Tumble mustard. Local exotic annual; rare f=Cruciferae Mustard 
Solanum douglasii Dunal. Nightshade. Local herbaceous perennial; common f=Solanaceae Potato, Nightshade 
Solanum elaeagnifolium Cav. Silver horsenettle, trompillo. Scattered f=Solanaceae Potato, Nightshade 
Solanum rostratum Dunal. Local exotic annual; rare on Greasewood Road f=Solanaceae Potato, Nightshade 
Sonchus asper (L.) Hill. Spiny sow thistle. Local exotic annual; uncommon f=Compositae Sunflower 
Sonchus oleraceus L. Sow thistle. Local exotic annual; uncommon in f=Compositae Sunflower 
Sorghum halepense (L.) Pers. Johnson grass. Scattered exotic perennial; f=Gramineae Grass 
Spermolepis echinata (Nutt.) Heller. Scale seed. Widespread annual; f=Umbelliferae Parsley 
Sphaeralcea ambigua Gray var. rosacea (Munz &amp; Johnst.) Kearney. f=Malvaceae Mallow 
Sphaeralcea angustifolia (Cav.) G. Don. Narrowleaf globe mallow. Local f=Malvaceae Mallow 
Sphaeralcea coulteri (Wats.) Gray. Coulter globe mallow. Scattered f=Malvaceae Mallow 
Sphaeralcea emoryi Torr. var. californica (Parish) Shinners [S. e. f=Malvaceae Mallow 
Sphaeralcea hastulata Gray. [S. subhastata Coult. var. thyrsoidea f=Malvaceae Mallow 
Sphaeralcea laxa Woot. &amp; Standl. Caliche globe mallow. Widespread f=Malvaceae Mallow 
Sphinctospermum constrictum (Wats.) Rose. Local annual; rare on rocky f=Leguminosae Pea 
Sporobolus airoides Torr. Alkali sacaton. Local perennial; uncommon f=Gramineae Grass 
Sporobolus contractus A. S. Hitchc. Spike dropseed. Scattered perennial; f=Gramineae Grass 
Sporobolus cryptandrus (Torr.) Gray. Sand dropseed. Local perennial; f=Gramineae Grass 
Sporobolus wrightii Munro ex Scribn. Sacaton. Local perennial; common f=Gramineae Grass 
Stemodia durantifolia (L.) Swartz. Local annual; rare in King Canyon; f=Scrophulariaceae Figwort 
Stephanomeria pauciflora (Torr.) A. Nels. Desert straw. Widespread f=Compositae Sunflower 
Stipa speciosa Trin. &amp; Rupr. Desert needlegrass. Local perennial; f=Gramineae Grass 
Streptanthus carinatus Wright. [incl. Streptanthus arizonicus Wats.]. f=Cruciferae Mustard 
Stylocline gnaphalioides Nutt. Everlasting nest straw. Local annual; f=Compositae Sunflower 
Stylocline micropoides Gray. Desert nest straw. Scattered annual; f=Compositae Sunflower 
Stylocline sonorensis Wiggins. Sonoran nest straw. Local annual; sandy f=Compositae Sunflower 
Talinum aurantiacum Engelm. Flame flower. [incl. T. angustissimum f=Portulacaceae Portulaca 
Talinum paniculatum (Jacq.) Gaertin. Pink baby breath. Local herbaceous f=Portulacaceae Portulaca 
Tamarix ramosissima Ledeb. [T. chinensis Loureiro, T. pentandra Pall. f=Tamaricaceae Tamarix 
Tecoma stans (L.) H.B.K. Yellow trumpet bush. Local shrub; uncommon f=Bignoniaceae Bignonia 
Tephrosia tenella Gray. Local herbaceous perennial or annual; common f=Leguminosae Pea 
Tetraclea coulteri Gray. Local herbaceous perennial; uncommon on disturbed f=Verbenaceae Vervain 
Teucrium cubense Jacq. Small coast germander. Local annual, uncommon f=Labiatae Mint 
Thamnosma texana (Gray) Torr. Local herbaceous perennial; uncommon f=Rutaceae Rue 
Thysanocarpus curvipes Hook. [Thysanocarpus amplectans Greene]. Lacepod. f=Cruciferae Mustard 
Tidestromia lanuginosa f=Amaranthaceae Amaranth 
Tillaea erecta H. &amp; A. [Crassula connata Miers]. Pigmy weed. Local f=Crassulaceae Orpine 
Tiquilia canescens (DC.) A. Richardson. [Coldenia canescens DC.]. f=Boraginaceae Borage 
Trianthema portulacastrum  f=Aizoaceae Carpet Weed 
Tridens eragrostoides (Vasey &amp; Scribn.) Nash. Local perennial; f=Gramineae Grass 
Tridens muticus (Torr.) Nash. Slim tridens. Widespread perennial; f=Gramineae Grass 
Triodanis biflora (R. &amp; P.) Greene. Local annual; rare east of f=Campanulaceae Bellflower 
Trisetum interruptum Buckl. Prairie trisetum. Local annual; Tucson f=Gramineae Grass 
Tritecum aestivum L. Wheat. Local exotic annual; rare along north f=Gramineae Grass 
Trixis californica Kellogg. Widespread subshrub; very common on rocky f=Compositae Sunflower 
Tumamoca macdougalii Rose. Tumamoc globeberry. Probably scattered f=Cucurbitaceae Gourd 
Typha domingensis Pers. Cattail. Local herbaceous perennial; very common, f=Typhaceae Cattail 
Vauquelinia californica (Torr.) Sarg. Arizona rosewood. Local shrub; f=Rosaceae Rose 
Verbena gooddingii Briq. [Glandularia gooddingii (Briq.) Solbrig]. f=Verbenaceae Vervain 
Verbena neomexicana (Gray) Small. Hillside vervain. Local herbaceous f=Verbenaceae Vervain 
Verbesina encelioides (Cav.) Benth. &amp; Hook. Cowpen daisy. Local f=Compositae Sunflower 
Veronica anagallis-aquatica L. Water speedwell. Local exotic annual; f=Scrophulariaceae Figwort 
Veronica peregrina L. ssp. xalapensis (H.B.K.) Pennell. Necklace weed. f=Scrophulariaceae Figwort 
Vicia ludoviciana Nutt. [V. exigua Nutt.]. Vetch. Scattered annual f=Leguminosae Pea 
Viquiera annua (Jones) Blake. Annual goldeneye. Local annual; uncommon f=Compositae Sunflower 
Vulpia microstachys (Nutt.) Benth. var. ciliata (Beal) Lonard &amp; f=Gramineae Grass 
Vulpia myuros (L.) K. C. Gmelin. [Festuca myuros L.]. Rattail fescue. f=Gramineae Grass 
Vulpia octoflora (Walt.) Rydb. [Festuca octoflora Walt.]. Sixweeks f=Gramineae Grass 
Yabea microcarpa (Hook. &amp; Arn.) K.-Pol. [Caucalis microcarpa H. f=Umbelliferae Parsley 
Yucca baccata Torr. var. brevifolia f=Agavaceae Agave 
Yucca elata  f=Agavaceae Agave 
Zephyranthes longifolia Hemsl. Rain lily. Local herbaceous perennial; f=Liliaceae Lily 
Zinnia acerosa (DC.) Gray. [Zinnia pumila Gray]. Desert zinnia. Widespread f=Compositae Sunflower 
Ziziphus obtusifolia (Hook. ex. T. &amp; G.) Gray var. canescens (Gray) f=Rhamnaceae Buckthorn