sus truncatus basi rotundatus, costis humilibus filiformi- 
bus; vittae et seminum superficies non visae: chromoso- 
matum numerus 7 = 20. 
Small, compact perennials from a fleshy taproot, 8-25 
em. high, the stem simple or few-branched, very sparsely 
leafy, glabrous throughout; basal leaves deltoid-orbicu- 
lar, 1-8 em. long, 1.5—5 cm. broad, trifoliate with 8 oval 
to orbicular, obtuse, lobed to pinnatifid leaflets 1-2 cm. 
in diameter; petiole 1-8 cm. long, narrowly scarious- 
sheathing: cauline leaves like the basal but reduced up- 
ward, the sheaths slightly dilated; peduncles few, alter- 
nate, slender, up toe 2 cm. long, but most umbels lateral 
and sessile or subsessile; involucre 0, or of a single trifid 
bract; rays 2-5, filiform, spreading-ascending, 6-25 mm. 
long; involucel 0; fertile pedicels 0-2 (many umbellets 
staminate), 8-4 mm. long; flowers greenish-yellow; sty- 
lopodium depressed, not evident: styles very short; 
sarpophore 2-cleft to base; immature fruit ovoid-orbicu- 
lar, 1.5 mm. long, 2 mm. broad, truncate at apex, 
rounded at base, the ribs low, filiform: vittae and seed 
face not seen; chromosome number r= 20. 
Type. Chihuahua: Municipio de Guazapares, among Pinus ponderosa, 
P. leiophylla, Quercus sp. and Arbutus sp., on recently logged ridge, 
elevation 8100 feet, off road northwest of Estaci6n San Rafael to Las 
Lagunitas, 21 July 1974, Robert A. Bye, Jr. 6376 (GH: holotype; 
ECON, UC). 
The plant was rather abundant but very local on slopes 
that had recently been disturbed by logging operations. 
Donnellsmithia silvicola appears to be most closely re- 
lated to D. serrata (C. & R.) Math. & Const. and D. 
dissecta (C. & R.) Math. & Const., both species of south- 
ern Mexico. It is unlike both in its lower stature and 
glabrous foliage. From the former, it differs also in its 
shorter rays; from the latter, in its lack of an involucel. 
The most striking disparity, however, is in its uniquely 
distinctive leaf form. 
[ 228 | 
