432 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
KEY TO THE GENERA. 
Stamens 5; plants covered with stinging hairs...........-. 1. CEVALLIA (p. 432). 
Stamens numerous; plants rough-hispid with barbed or 
hooked but never stinging hairs. 
Placente: with horizontal lamellee between the seeds; 
seeds flat, winged.........-..---2----1-----eee 2. Nutra. (p. 482). 
Placente without lamelle; seeds not winged. 
Seeds prismatic, muricate; leaves sessile........... 3. ACROLASIA (p. 435). 
Seeds pyriform or ellipsoid, striate with parallel 
curved lines; leaves petiolate (petioles some- 
times very short)...........-..2---2-2-200- 4. MENTZELIA (p. 436). 
1, CEVALLIA Lag. 
Canescent branched perennial herbs armed with stinging hairs; leaves alternate, 
sessile, sinuate-pinnatifid; flowers in terminal heads; tube of the calyx short, with 
erect linear lobes; petals 5, plumose; stamens 5, erect, with very short filaments; fruit 
dry, indehiscent, 1-seeded. 
1. Cevallia sinuata Lag. Var. Cienc. 21: 35. 1805. 
Type Locality: Mexico. 
Ranae: Western Texas to southern Arizona and southward. 
New Mexico: Rincon; mesa west of Organ Mountains; Dog Spring; Lake Valley; 
Lordsburg; Hatchet Ranch. Dry mesas, especially along arroyos, in the Lower Sono- 
ran Zone. 
. 2. NUTTALLIA Raf. 
Herbaceous short-lived perennials (sometimes annuals) with white stems, at first 
rough, becoming smooth and shining below, or the epidermis exfoliating; leaves simple, 
alternate, more or less densely rough-hirsute with stiff, barbed or hooked, white hairs; 
hypanthium mostly campanulate, becoming hemispheric to cylindric in fruit; sepals 
5, persistent; petals 5 or with 5 additional petal-like staminodia, of some shade of yel- 
low (often described as white); stamens numerous, the outer rows of filaments often 
petaloid; capsules 1-celled with parietal placentze lamellated between the flattened, 
winged, finely tuberculate seeds. 
KEY TO THE SPECIES. 
Leaves pinnately toothed or lobed. 
Lobes of the leaves linear, several times as long as broad, 1 to 2 
mm. wide. 
Plants small, 30 to 50 cm. high; flowers pale yellow, small. 1. N. gypsea. 
Plants taller, spreading, 60 to 80 cm. high; flowers deep 
golden yellow, larger..................000.22--0005 2. N. laciniata. 
Lobes of the leaves oblong, hardly more than twice as long as 
broad, 2 to 3 mm. wide. 
Petals bright yellow; some of the leaves entire. 
Some of the leaves oblanceolate; plants stout; capsules 
nearly as broad as long..............-.--------- 12. N. integra. 
All leaves linear; plants slender; capsules twice as long 
as broad.......-----20--- eee eee ee eee eee ee eees 13. N. springeri. 
Petals whitish or pale yellow; leaves all lobed or toothed. 
Lobes of the leaves few, 1 to 3 on each side, often en- 
tirely wanting; plants cespitose.............-.- 3. N. perennis. 
