

FLOWERING PLANTS AXD FERNS OF ARIZONA 843 



Some of the native species afford excellent forage for sheep and 

 cattle. The seeds become mucilaginous when wet and are produced 

 in such quantity where the plants are abundant as to cement the sand 

 grains after rain, forming a thin crust on the surface of the soil. 

 Seeds of the Arizona species that are known as Indianwheat (P. 

 fastigiata, P. purshii) are sometimes gathered and used as a substitute 

 for the psyllium seeds of commerce,, which are obtained from an Old 

 World species. Plantago psyllium. 



Key to the species 



1. Flowers more or less dioecious or polygamous, many of them cleistogamous the 



corolla remaining closed and its lobes erect or connivent), other flowers 



with spreading corolla lobes and exserted stamens; plants annual or biennial; 



leaf blades often coarsely dentate or cleft (2) . 



2. Leaves and scapes inconspicuously pubescent or glabrate, the hairs short, 



mostly appressed; leaf blades filiform or linear, less than 5 mm. wide; 



spikes loosely flowered, often interrupted below; calyx glabrous; corolla 



white or pale straw-colored; capsule with 8 or more seeds. 



1. P. HETEROPHYLLA, 



2. Leaves and scapes copiously villous or subhirsute; leaf blades elliptic or 

 oblong-oblanceolate, seldom less than 8 mm. wide; spikes usually densely 

 flowered; calyx villous or subhirsute; corolla buff or orange-colored; 

 capsule 2- to 4- seeded (3). 



3. Capsule 3-seeded; plant flowering in late summer 2. P. hirtella. 



3. Capsule usually 2-seeded; plants flowering in spring (4). 



4. Bracts and sepals obtuse; fruiting calyx less than 3 mm. long; mature 

 seeds yellowish brown, less than 2 mm. long, deeply concave on 



the ventral face 3. P. virgixica. 



4. Bracts and sepals acute or apiculate; fruiting calyx 3 to 4 mm. long; 

 mature seeds dark red, 2.5 to 3 mm. long, flat to slightly concave 



on the ventral face 4. P. rhodosperma. 



1. Flowers not dioecious, all perfect, none cleistogamous; corolla lobes perma- 

 nently spreading or reflexed (5). 

 5. Leaf blades broadly lanceolate, oblanceolate, or broader, seldom less than 

 10 mm. wide; plants glabrous or loosely pubescent, not sericeous or 

 lanate, usually perennial, with a thick caudex (6). 

 6. Spikes short-conic, becoming oblong, very dense, 1 to 6 cm. long at 

 maturity; leaf blades lanceolate or oblong-lanceolate, entire or den- 

 ticulate; seeds 2, concave on the ventral face 5. P. laxceolata. 



6. Spikes cylindric, moderately dense or rather loose, usually 6 cm. long or 

 longer at maturity (7). 

 7. Leaf blades broadly ovate, abruptly contracted at base; scapes seldom 

 woolly at base; seeds several or numerous, not more than 1 mm. long, 

 angulate, finely reticulate, not concave ventrally. 6 . P. major. 

 7. Leaf blades lanceolate, oblanceolate, or elliptic, tapering at base; scapes 

 usually woolly at base; seeds not more than 4, 2 to 3 mm. long, 

 rounded on the back, somewhat concave ventrally _ 7. P. eriopoda. 

 5. Leaf blades linear or lanceolate, commonly much less than 10 mm. wide; 

 plants copiously silky-villous, sericeous, or lanate (except in P. wrighti- 

 ana), annual or winter annual; spikes cylindric at maturity; seeds 2, 

 deeply concave on the ventral face (8). 

 8. Bracts subulate or narrowly lanceolate, not or very indistinctly scarious- 

 margined, at least the lower ones commonly longer than the calyx. 



8. P. PURSHII. 

 8. Bracts broadly lanceolate to nearly orbicular, conspicuously scarious- 

 margined, none longer than the calyx (9). 

 9. Leaves not at ail rigid, conspicuously whitish sericeous or lanate, not 

 noticeably discolored in drying; spikes at maturity 1 to 4 cm. long, 

 seldom more than 4 times as long as wide; lowest bracts much like 

 the sepals, broadly ovate or nearly orbicular, broadly scarious- 

 margined to the apex, the scarious portion forming more than one- 

 half of the area of the bract; seeds reddish brown, somewhat shiny. 



9. P. FASTIGIATA. 



