BOTANY. 87 
inclusus, simplicissimus. Ovarium nullum. Achenia obcompresso-plana, ala laciniata circum- 
data, cum squamis fructiferis petaloideo-scariosis iis majoribus involucrum externum multoties 
superantia. Pappus brevis, plurisetulosus, deciduus vel evanescens.— Herba humilis, ramosa, 
hispidulo-canescens, alternifolia; capitulis racemoso-paniculatis, fructiferis cernuis. 
D. CANESCENS. In the sandy desert of the Gila and of the Colorado; Emory. A small speci- 
men of this curious plant was brought home by Col. Emory from his reconnaissance of the Gila, 
etc., іп 1846; but it has not again been met with. The base of the plant is unknown. Leaves, 
at least the upper ones, alternate, oval, obtusely dentate, on slender petioles, scabrous or hispid, 
and- when young canescently villous on both sides; those of the flowering branches gradually 
reduced to small and spatulate bracts. Heads short-pedicelled, arranged in loose and nearly 
leafless spikes or racemes, which are panicled at the summit of the stem in anthesis, only one 
and a half lines long; but in fruit the whitish and somewhat glandular and erose pair of inner 
involucral scales become three or four lines long and almost as broad ; they are loosely appressed 
to the achenia which they subtend, and appear to be deciduous with them at maturity. The 
mature achenia are about 3 lines long, and 2 lines wide, including the strong laciniate-toothed 
and incised wing, both faces slightly hispid, and carinately one-nerved in the middle ; near the 
summit of the nerve of the inner, and sometimes of the outer face also, a small crest often appears 
like the rudiments of an anterior and posterior wing. Although the full-grown achenia com- 
monly appear destitute of a pappus, yet in the flowering state there is always a rather con- 
spicuous ring of short bristles surrounding the base of the naked style, and traces of it are 
generally discernible at maturity. The bristles are united at the base into a ring, and appear 
to form a true pappus. They consist, however, of single rows of cells, exactly like the short 
and fine bristly hairs which fringe the margin of the inner involucral scales. It will be seen 
that the genus belongs to the division Ives of De Candolle. The name (from д/с, two, and 
Kop:o, а bug,) alludes to the two achenia appearing like bugs, or like the achenia of some species 
of Coreopsis. 
AMBRoISA PSILOSTACHYA, DC. Prodr. 5, p. 526; Gray, Pl. Wright, 1. с. А. coronopifolia, Torr. 
& Gray. Common, from Texas to Sonora. It occurs both with unarmed and tuberculate fruit.* 
FRANSERIA TENUIFOLIA, Var, TRIPINNATIFIDA, Gray, l.c. Common from Texas to Sonora. This 
is both Ambrosia fruticosa (excl. var. 8) and A. confertiflora of De Candolle; but none of the 
forms in Berlandier's collection are at all shrubby. 
Franserta HOOKERIANA, Nutt. El Paso to Sonora, etc. ; common. 
FnaNsERIA DUMOSA, Gray, in Frémont, 2d Exped. p. 816, var. ALBICAULIS .F. albicaulis, Torr. 
Pl. Frém. р. 16. Desert of the Colorado of the West; common; Thurber, Bigelow, Schott. 
FRANSERIA DELTOIDEA, Torr. Pl. Frémont, p.15. Valley of the Gila; Parry. A well-marked 
species ; but it should be compared with F. chenopodifolia, Benth. Bot. Voy. Sulph., from lower 
California. 
® The following is an undescribed species, occurring in Berlandier's терийг : 
AMBROSIA EGE "€ nov.): humilis, pube minuta canescens; ramis foliosis ; foliis oblongo-lanceolatis seu 
oblongo-spathulatis i ilibus, superioribus flores foemineos fulcrantibus ; capitulis masculis elongato-racemosis 
өй: fructibus 4-5- -spinosis, spinis crassis.—San Fernando, Cohahuila, 1543, 3043.--А perennial herb, apparently 
not over а foot in height, considerably branched. Leaves an inch or rather more in length, 3 to 6 lines wide, all undivided 
and entire, whitened both sides with a fine and short appressed pubescence. Sterile heads 2g lines long, nearly glabrous, 
armed with four or five short and stout spines, which are about the length of the similar beak. 
