100 ONAGRACE^. (EVENING-PRIMROSE FAMILY.) 



2. M. verticillatum, L. Like the last, but fiord leaves much longer 

 than the flowers and pectinate pinnatijid. Snake River ( Coulter) ; in the 

 Atlantic States and northward. 



ORDER 30. LYTIIBACE^E. (LOOSESTRIFE FAMILY.) 



Herbs with simple and entire leaves, calyx tubular or campanulate 

 and free from the ovary and capsule, but enclosing it, the petals and 

 definite stamens borne in its throat, a single style, and numerous small 

 seeds on a central placenta. Distinguished from Haloragece and Ona- 

 gracea by the free ovary, and from the former also by the numerous 

 seeds. 



1. Ammannia. Calyx barely 4-angled, short. Petals 4 or none. Stamens 4 or 8. Capsule 



globular, bursting irregularly. Leaves opposite. 



2. Liythmm. Calyx striate, cylindrical. Petals commonly 6 (4 to 7). Stamens as many 



or twice as many. Capsule oblong or cylindraceous. 



1. AMMANNIA, Houston. 



Calyx 4-toothed, with as many intermediate small tooth-like processes. 

 Petals as many, small and fugacious, or none. Low and smooth annuals, 

 with 4-angled steins, sessile leaves, and small axillary flowers. 



1. A. latifolia, L. Stems erect: leaves linear-lanceolate, with a broad 

 auricled base : flowers 1 to 5 in each axil, mostly closely sessile. Milk River, 

 N. Montana; also in Nevada, California, and the S. Atlantic States. 



2. LYTHRUM, L. LOOSESTRIFE. 



Calyx 4 to 7-toothed, with intermediate tooth-like processes. Petals oblong- 

 obovate, often conspicuous. Erect slender herbs, with angled stems, and 

 axillary mostly solitary flowers. 



1. L. alatum, Pursh. Tall and wand-like perennial, smooth: branches 

 with margined angles : leaves from oblong-ovate to lanceolate, the upper 

 scattered, not longer than the flowers, which are small and nearly sessile in 

 the axils : proper calyx-teeth often shorter than the intermediate processes : 

 petals purple. From Colorado to the N. Atlantic States, and southward. 



ORDER 31. ONAGBACE^E. (EVENING-PRIMROSE FAMILY.) 



Herbs, with perfect symmetrical flowers, the parts being most com- 

 monly in fours, the calyx-tube adnate to the ovary and its lobes often 

 colored, the petals borne on its throat or at the sinuses, the cells of the 

 ovary usually of the same number, the stamens as many or twice as 

 many, and styles always single. Leaves simple, but sometimes lobed 

 or divided, either alternate or opposite : no stipules. Flowers often 

 showy. In ours the limb of the calyx is deciduous. 



