cuspidate ; scales of the involucre scarcely united; the exterior linear-lanceolate,
cuspidate, ciliate, spreading, nearly equalling the scarious or colored interior
series; chaff obtuse; achenia 4-angled, tapering into a very long up-
wardly scabrous beak, crowned with 2 spreading awns.—II. B. &■ K . nov.
gen. spec. 4. p. 240 ; DC. ! prodr. 5. p. 606. Bidens Berteriana, Spreng.
syst. 3. p. 454 ; DC. ! in Wight, contrib. p. 19.
Ke/ West, Mr. Blodgett! A common West Indian species ; also naturalized
in the E ast Indies— U Rays rose-color, 3-cleft at the summit,
Ion106 y l0Dger than the involucre. Achenia (about 20) nearly an inch
103. COSMIDIUM. Torr. 8f Gray, mss. ; Nutt, in brans. Amer. phil.
soc. (n. ser.) 7. p. 361.
Heads many-flowered; the ray-flowers about 8, neutral, or sometimes
wanting; those of the disk tubular, perfect. Involucre double, each of 8
scales; the interior oblong-ovate, somewhat membranaceous, united to the
middle, much larger than the exterior. Receptacle flat; the chaff scarious,
oblong, obtuse, with 2 approximate colored nerves, shorter than the flowers,
partly investing the achenia, and deciduous with them. Corolla of the disk
with a very slender tube, and a deeply 5-cleft limb; the segments long and
linear, recurved. Anthers and style as in Cosmos (the base of the latter
dilated into a conspicuous bulb.) Achenia linear-oblong (obscurely angled
when young), terete or slightly obcompressed, a little incurved and tubercu-
late on the back when mature, not rostrate, the abrupt summit crowned with
2 dentiform retrorsely pectinate-ciliate (persistent ?) awns—Annual and perennial
dichotomous or brachiate glabrous herbs, with slender branches naked
at the summit, and terminated by rather small heads. Leaves opposite,
somewhat fleshy (the lower petioled, the upper nearly sessile), 1- 2-pinnate-
ly parted ; the divisions or lobes linear-filiform, canaliculate, entire. Rays
light yellow; the disk-flowers purple ; the chaff white.
1 . C. fllifolium (Torr. & Gray 1 1. c .) : lower leaves twice ternately or
pinnately divided ; the upper simply 3-5-divided, or the uppermost simple';
the divisions attenuate-filiform; scales of the interior involucre with broad
scarious margins, united nearly to the middle, longer than the linedr-subu-
late exterior scales; rays obovate, 3-toothed ; achenia crowned with 2 triangular
subulate concave at length divaricate short awns or teeth.—Nutt. ! 1. c.
Coreopsis filifolia, Hook.! hot. mag. t. 3505; DC.!prodr. 7. p. 290.
Plains of Arkansas, on the Red River, &c., Nultall! Dr. Leavenworth !
Dr. Engelmann ! Texas, Drummcmd! May-July— ® Hook. U Nutt.
Stem 1-3 feet high, much branched. Heads nearly as large as in Coreopsis
tmctoria. Achenia about 3 lines long, crustaceous when ripe, obe or both
sides smooth and even when young: the awns or teeth scarcely a line in
length, fringed with yellow reflexed bristly hairs, apparently persistent. Chaff
closely investing the back of the achenia— We had provisionally appended
this group to Cosmos (not to Coreopsis, as Mr. Nuttall by some misapprehension
states), to which it is most allied, notwithstanding the yellow rays
(which are also found in C. sulphureus) and erostrate achenia.
2. C. gracile (Torr. & Gray ! 1. c .) : leaves pinnately or pedately about
5-parted, with narrowly linear rigid lobes; the uppermost nearly simple;
scales of the inner involucre united above the middle, obtuse, without scarious
margins, th,e exterior ovate, obtuse, very short; rays none; ovaries
oblong-linear, crowned with 2 subulate retrorsely pectinate-hispid (deciduous?)
awns.—Bideus gracilis, Torr. ! in ann.lyc. New York, 2. p. 215.
Upper Arkansas, on the Canadian River, Dr. James !—If Stems 2 feet
high, branched from the base, dichotomous and naked at the summit, striate.
Chaff &c. as in the preceding. Awns stout, concave, about the length of
the tube of the corolla.—The single Specimen brought by Dr. James, the
only one extant, is not very perfect. Perhaps it sometimes bears ray-
flowers.
104. BIDENS. Linn.; Geertn.fr. t. 167; DC. prodr. 5. p. 593.
Heads many-flowered ; the ray-flowers (3-8) neutral, often inconspicuous
or wanting ; those of the disk tubular, perfect. Involucre double; the scales
dissimilar or nearly similar, the exterior frequently large and foliaceous.
Receptacle flattish; the chaff deciduous with the fruit. Corolla with a slender
tube, and an infundibuliform-campanulate 5-toothed limb. Branches of
the style hairy at the summit, terminated by an acute or subulate cone.
Achenia obcompressed, or slender and more or less 4-sided, often attenuate
or rostrate at the summit, crowned with 2-4 (rarely 5-6) rigid and persistent
retrorsely barbed or hispid awns.—Annual or sometimes perennial (mostly
American) herbs; with opposite, incised, serrate, or divided leaves, feather-
veined (the numerous primary veins often running to the sinuses) and reticulated.
Flowers mostly yellow or yellowish: the anthers pale or brownish.
§ 1. Achenia flat, oval or cuneiform, not attenuated at the summit; the
margins ‘usually ciliate or hispid mostly in a downward direction.—
Pr.ATYCARP.EA, DC.
1 . B. frondosa (Linn.) : glabrous or slightly hairy ; lower leaves pinnately
5-, the upper commonly 3-divided ; the divisions distinct and mostly pe-
tiolulate, lanceolate, or the terminal one ovate-lanceolate, acuminate, coarsely
serrate (rarely 3-lobed or parted) ; heads discoid, pedicellate ; scales of the
exterior foliaceous involucre longer than the head, mostly acute, conspicuously
ciliate towards the base ; achenia obovate-cuneiform, 2-awned, pubescent
and ciliate with chiefly erect hairs.—Linn.! spec. (ed. 2) 2. p. 1166;
Michx.! fl. 2. p. 136; WiUd.! spec. 3. p. 1718; Pursh, l. c .; Ell. sk. 2. p.
431; Hook. fl. Bor.-Am. 1. p. 314; Bigel. fl. Bost. ed. 2. p. 294 ; Dar-
lingt. ! fl. Cest.p.486; D C .! l.c.
Moist fertile soil, throughout Canada! and the United States! abounding
around barn-yards and moist corn-fields, where it is a very troublesome
weed. Ju ly -S ep t.—Stem 2-6 feet high, branched. Petioles, and often the
lower surface of the leaves, a little hairy. Scales of the outer involucre 8-12,
varying from twice to six limes the length of the disk ; the inner ovate-lanceolate,
brownish. Flowers greenish-yellow. Margins of the achenia upwardly
ciliate, except near the summit, where the bristles are usually re-
trorse.—Stick-tight. Burr-Marigold.
2. B. connata (Muhl.): glabrous ; leaves lanceolate or. oblong-lanceolate,
acute or acuminate, sharply serrate, tapering into margined petioles, slightly
connate at the base; the lower ones often ternately divided ; the lateral seg