76. PARTHENIUM. Linn.; Geertn. fr . t. 168 ; DC. prodr. 5. p. 531.
Heads many-flowered ; the ray-flowers 5, pistillate, fertile, somewhat obscurely
ligulate, one in the axil of each inner scale of the involucre ; those of
the disk tubular, sterile by the abortion of the style. Involucre hemispherical,
in a double series ; the exterior ovate ; the interior nearly orbicular. Receptacle
conical or somewhat cylindrical, covered with membranaceous chaffy
scales, which are dilated above and somewhat cucullate, partly sheathing
the flowers of the disk, tomentose at the summit. Corolla of the ray very
short, obcordate, persistent or marcescent; of the disk tubular, somewhat
dilated above. Stamens inserted towards the base of the corolla: anthers
slightly united. Style of the sterile flowers undivided : the branches of the
fertile style semiterete, obtuse. Achenia (of the ray) compressed, oval or
obovate, smooth, surrounded by a filiform callous margin, which is firmly
coherent at the base with the involucral scale and with a contiguous chaffy
scale of the receptacle on each side, at length tearing away from the ache-
nium. Pappus 2-squamellate, or somewhat aristate, sometimes nearly obsolete.—
Herbs or suffrutescent (American) plants, somewhat various in
habit, canescent or hirsute-scabrous, with alternate undivided or 1-2-pinnately
cleft leaves. Heads corymbose-cymose or panicled, rarely solitary. Flowers
whitish.
§ 1. Pappus of 2 very small and slender or awn-like squamellee, sometimes
obsolete : perennial or suffrutescent: leaves toothed or somewhat incised, undivided.—
P artheniastrum, Dill., DC.
1. P . integrifolium (Linn.) : stem herbaceous, hirsute-pubescent; leaves
hispid-scabrous, ovate-oblong or lanceolate-oblong, doubly crenate orcrenate-
toothed, or sometimes incised ; the upper ones sessile or partly clasping ; the
lower petioled, often deeply incised at the base ; heads numerous, tomentose,
corymbed ; exterior scales of the involucre somewhat acute.—Linn.! spec.
2. p . 988; Lam. ill. t. 766 ; Michx. ! ft. 2. p . 147 ; Willd. hort. Berol. t.
4 ; Schlcuhr, handb. t. 293 ; Nutt. gen. 2. p. 183; E ll.! sk. 2. p. 474 ;
DC. 1. c. Partheniastrum Helenii folio, Dill. Elth. t. 226, ƒ. 292. Ptar-
mica Virginiana &c., Pluk. aim. t. 53, f . 6, Up 219, f . 1.
Dry soil, Maryland! Virginia! to Alabama! and west to Missouri!
Louisiana! and Texas! July-Sept.—Stem 1-2 feet high. Lower leaves
3-5 inches long. Heads crowded, about 4 lines in diameter; the scales
closely appressed. Ray inconspicuous.
§ 2. Pappus of 2 oblong obtuse membranaceous squamellee: root annual:
leaves bipinnatifid.—A rgtrochjeta, Cav., DC.
2. P. Hysterophorus (Linn.): hirsute-puberulent and somewhat canescent,
diffusely branched or decumbent; leaves variously bipinnatifid; the uppermost
linear and undivided ; heads (very small) paniculate; exterior scales of
the involucre somewhat acute.—Linn. 1. c .; hot. mag. t. 2275 ; Hook, in
compan. to bot. mag. 1. p . 99; DC.! 1. c. Argyrochseta bipinnatifida, Cav.
ic. 4. p. 54, t. 378. Villanova bipinnatifida, Ort. dec. p. 48, t. 6.
Banks of streams, New Orleans, Drummond, Dr. Ingalls ! Texas, Ber-
landier! St. Augustine, Florida, Baldwin ! Key West, Mr. Blodgett!
Also a native of Mexico and the West Indies.—Leaves resembling those of
Ambrosia artimesiaefolia.
§ 3. Pappus of 2 oblong-lanceolate membranaceous squamellee, nearly the
length of the short truncate tubular corolla: ceespitose, dwarf: heads solitary
and nearly sessile among the spatulate-linear canescent leaves at the
summit of each division of the ligneous caudex!—B olophyta, Nutt.
3. P. alpinum: acaulescent; caudex branched, densely caespitose, and
crowned with the vestiges of former leaves and with a tuft of white hairs ;
leaves densely tufted, entire, silvery-canescent; corolla_ of the ray scarcely
exserted, truncate, slightly 2-crenulate.—Bolophyta alpina, Nutt. ! in trans.
Amer. pMt. soc. (n. ser.) 7. p. 347.
In the Rocky Mountains, towards the sources of the Platte, in about lat.
42°, on shelving rocks at the summit of a lofty hill, near the place called the
» Three Butes’ by the Canadians, 7000 feet above the level of the sea. Nut-
tall! June.—Caudex fusiform, sending off several closely matted crowns of
leaves ; the latter an inch or an inch and a half in length, scarcely a line
wide, tapering into short petioles, 1-nerved. Heads concealed among the
leaves, about as large as those of P. integrifolium, and entirely similar in
structure ; except that the rays, if they may be so called, are shorter, entirely
tubular, with an obscure emargination anteriorly and posteriorly. The pappus,
which escaped Mr. Nuttall’s notice, consists of a scarious ovate-lanceolate
or triangular scale-like auricle or tooth on each side, which perhaps
withers away as the achenium ripens. Excepting the habit, therefore, we
find nothing whatever to distinguish this little plant from Parthenium, beyond
the more reduced corolla of the ray.
Div. 5. I t e j e , DC.—Fertile and sterile flowers in the same heads, all
tubular, or the former rarely apetalous. Pappus coroniform, 4-awned, or
none. Anthers approximate but distinct: filaments inserted towards the
base of the corolla. Style of the fertile flowers mostly 2-parted.
77. CYCLACHiENA. Fresenius, ind. sem. hort. Franc. 1836,p. 4, Spin
Linneea, 12, suppl. p. 78.
(Polygamo-subdioecious; the barren plant similar to the fertile, but not
fertilizing its ovaries.) Fertile and sterile flowers in the same heads; the
former 5, in the axils of the inner scales of the involucre, with no corolla or a
mere rudiment; the latter 10-15, with an obconical 5-toothed corolla, (nearly
destitute of proper tube); the central ones abortive. Scales of the flatfish
hemispherical involucre usually 10, in 2 series ; the exterior 5, ovate, somewhat
acuminate, thickish, herbaceous ; the interior dilated-obovate, truncate,
membranaceous, at length loosely wrapped around the achenia. Receptacle
small, flat; the chaff linear-spatulate, usually wanting towards the centre.
Anthers slightly united, tipped with an inflexed mucronate appendage.
Style of the fertile flowers deeply 2-cleft, linear, acutish; in the sterile
flowers undivided, radiate-penicillate at the apex. Achenia obovate, obcom-
pressed, somewhat turgid, not margined, glabrous, entirely destitute of pappus
; the staminate flowers with no rudiments of ovaries.—A tall and coarse