1 20 Flora of the Palouse Region 



0. polyacantha Haw. Prostrate, frequently in large tufts: joints of the 

 stem flattened, orbicular or oblong, 5-12 cm. long, pale-green: leaves 

 minute, 3-4 mm. long: cushions pale bristly: spines 4-8, whitish, usually 

 red-tipped, 5-20 mm. long, mostly deflexed: flowers yellow, 4-5 cm. broad: 

 fruit ovate, dry, 2.5 cm. long, with a shallow saucer-like apex. Rocky and 

 sand}- places, banks of Snake River. Our form is not typical. 



Family 53. L,YTHRACEAE. 



Herbs: leaves mostly opposite and entire: flowers axillary or 

 whorled, perfect: calyx enclosing bnt not united to the ovary: 

 petals as manj^ as the calyx-teeth, perig}mous, or none: stamens 

 4 14, on the calyx: style 1; ovary 2-4-celled; ovules numerous, 

 rarely few: fruit a membranous capsule; endosperm none. 



Flowers mostly more than one in the axils: capsule bursting irregularly. 



195. A.MMANNIA. 

 Flowers mostly solitary in the axils: capsule septicidally dehiscent, 



196. ROTALA. 



195. AMMANNIA. 



Low and inconspicuous smooth herbs: leaves opposite, narrow: 

 flowers small, 1 -several in the axils: calyx bell-shaped, usually 

 4-angled, 4-toothed and with 4 intermediate short tooth-like ap- 

 pendages in the sinuses: petals 4, small, early deciduous, or want- 

 ing: stamens 4-8: capsule globular, enclosed in the calyx, mostly 

 4-celled, bursting irregularly. 



A, COCCinea Rottb. Erect or ascending, glabrous, 5-30 cm. high, 

 branched below: leaves oblong-linear, acute or obtuse, auriculate-clasping at 

 the sessile base, entire, 2-4 cm. long: flowers 1-5 in the axils, sessile or nearly 

 so: petals broadly spatulate, truncate: style slender, about one-half as long 

 as the capsule. Sandy banks of Snake River at Almota, very rare. 



196. ROTALA. 



.Low annual mostly glabrous herbs: stems 4-angled: leaves op- 

 posite, sessile or sometimes petioled: flowers small, axillary, 

 mostly solitary: calyx 4-lobed: petals 4: stamens 4, short: ovary 

 free from the calyx, globose, 4-celled: capsule globose, enclosed 

 by the membranous calyx, 4-celled, septicidally dehiscent. 



R. ramosior Koehne. Annual, glabrous, simple or branched below, 5-15 

 cm. high, erect or ascending: leaves entire, oblong or spatulate, obtuse or 

 acute, 1-2 cm. long, narrowed into a short petiole at base, not auricled: 

 flowers mostly solitary in the axils: calyx 2-3 mm. long: petals minute: style 

 very short. Ranks of .Snake River at Almota, rare. 



