GERANIACE^E. (GERANIUM FAMILY.) 43 



forming an exterior cup-shaped calyculus : petals sulphur-yellow : styles united 

 almost to the top: capsule shorter than the sepals. From S. Colorado to the 

 Missouri River. 



3. L. Kingii, "Watson. Stems panicled above, shrubby at base: leaves 

 linear or narrowly oblong, obtuse: styles distinct: capsule somewhat exceeding 

 the sepals. Bot. King's Exp. 49. Mountains of Utah. 



ORDER 17. ZYGOPHYL,L,ACE^. 



Distinguished from allied orders by the opposite compound leaves, 

 with interposed stipules and entire dotless leaflets. Sepals 5, distinct. 

 Petals hypogynous, imbricated in the bud. Stamens (in ours) twice as 

 many as the petals and inserted with them. Ovary 5 to 12-celled, with 

 a single terminal style. Fruit dry. Ours are herbs or shrubs, with 

 solitary flowers on lateral or terminal naked peduncles, and ovary sur- 

 rounded at the base by a disk. 



1. Trlbulus. Leaves abruptly pinnate, 6 to 10-foliolate. Fruit tuberculate. Herbs. 



2. Larrea. Leaves 2-foliolate. Fruit densely hairy. Heavy-scented shrubs. 



1. TRIBULTJS, L. 



Sepals mostly persistent. Petals fugacious. Disk annular, 10-lobed. 

 Stamens 10, the alternate filaments a little shorter and with a gland at base 

 on the outer side. Ovary 5 to 12-celled. Fruit lobed, separating into roughly 

 tuberculate carpels. Loosely branched and hairy prostrate herbs, with ap- 

 parently axillary white or yellow flowers. 



1. T. maximus, L. Leaflets ovate-oblong, more or less oblique: sepals 

 very hairy, linear, acuminate : fruit beaked by a stout style. Kallstroemia 

 maxima, Torr. & Gray. Fremont County, Colorado (Brandegee), to S. Cali- 

 fornia and Texas. 



2. LARREA, Cav. CREOSOTE-BUSH. 



Sepals deciduous. Petals unguiculate. Disk 10-lobed. Filaments winged 

 below with a bifid scale on the inner side. Ovary 5-celled. Fruit globose, 

 shortly stipitate, separating into 5 hairy one-seeded carpels. Evergreen 

 heavy-scented shrubs, with nodose branches, and yellow flowers. 



1. L. Mexicana, Moric. Diffusely branched, 4 to 10 feet high, densely 

 leafy, of a yellowish hue : leaves nearly sessile ; the thick resinous leaflets 

 inequilateral, with a broad attachment to the rachis : sepals silky : scales 

 a little shorter than the filament, somewhat lacerate: fruit beaked by a 

 slender style. S. Colorado to California and Texas. 



ORDER 18. OEBANIACE^E. (GERANIUM FAMILY.) 



Leaves generally with stipules, either lobed or compound. Flowers 

 on axillary peduncles, regular (in ours) and the parts in fives. Stamens 

 mostly 10, often somewhat monadelphous. Ovary 5-celled ; with a cen- 

 tral axis. 



