Filaments slender. Calyx glandular inside. Leaves opposite.

3. Apocynum. Seeds comose. Corolla bell-shaped, appendaged within.

Filaments short, broad and flat. Calyx not glandular. Leaves opposite.

1. AMSNIA, Walt.

Calyx 5-parted, small. Corolla with a narrow funnel-form tube bearded inside, especially at the throat; the limb divided into 5 long linear lobes. Stamens 5, inserted on the tube, included; anthers obtuse at both ends, longer than the filaments. Ovaries 2; style 1; stigma rounded, surrounded with a cup-like membrane. Pod (follicles) 2, long and slender, many-seeded. Seeds cylindrical, abrupt at both ends, packed in one row, naked.--Perennial herbs, with _alternate leaves_, and pale blue flowers in terminal panicled cymes. (Said to be named for a _Mr.

Charles Amson_.)

1. A. Tabernaemontana, Walt. Loosely p.u.b.escent or hairy when young, soon glabrous; leaves from ovate-lanceolate to linear-lanceolate, taper-pointed; calyx-lobes short, awl-shaped; tube of the bluish corolla little longer than the lobes, the upper part either hairy when young or glabrous.--Low grounds, N. C. to S. Ind. and Mo., south to Fla. and Tex.

May, June.

2. TRACHELOSPeRMUM, Lemare.

Calyx 5-parted, with 3--5 glands at its base inside. Corolla funnel-form, not appendaged; limb 5-lobed. Stamens 5, included; filaments slender; anthers arrow-shaped, with an inflexed tip. Pods (follicles) 2, slender, many-seeded. Seeds oblong, with a tuft of down.--Twining plants, more or less woody, with opposite leaves and small flowers in cymes. (Name from t???????, _a neck_, and sp??a, _seed_, upon the supposition that the seed was beaked.)

1. T. difforme, Gray. Nearly herbaceous and glabrous; leaves oval-lanceolate, pointed, thin; calyx-lobes taper-pointed; corolla pale yellow. (Forsteronia difformis, _A. DC._)--Damp grounds, Va. to Fla. and Tex. April.

3. APoCYNUM, Tourn. DOGBANE. INDIAN HEMP.

Calyx 5-parted, the lobes acute. Corolla bell-shaped, 5-cleft, bearing 5 triangular appendages below the throat opposite the lobes. Stamens 5, on the very base of the corolla; filaments flat, shorter than the arrow shaped anthers, which converge around the stigma, and are slightly adherent to it. Style none; stigma large, ovoid, slightly 2-lobed. Fruit of 2 long (2--7') and slender follicles. Seeds comose, with a tuft of long silky down at the apex.--Perennial herbs, with upright branching stems, opposite mucronate-pointed leaves, a tough fibrous bark, and small and pale cymose flowers on short pedicels. (Ancient name of the Dogbane, composed of ?p?, _from_, and ????, _a dog_.)

1. A. androsaemiflium, L. (SPREADING DOGBANE.) Smooth, or rarely soft-tomentose, branched above; _branches divergently forking; leaves ovate, distinctly petioled; cymes loose, spreading_, mostly longer than the leaves; _corolla_ (pale rose-color, 4" broad) _open-bell-shaped, with revolute lobes, the tube much longer than the ovate pointed divisions of the calyx_.--Borders of thickets; common. June, July.

2. A. cannabinum, L. (INDIAN HEMP.) Glabrous or more or less soft-p.u.b.escent; stem and branches _upright or ascending_ (2--3 high), terminated by _erect and close many-flowered cymes_, which are usually shorter than the leaves; leaves from oval to oblong and even lanceolate, short-petioled or sessile, with rounded or obscurely cordate base; _corolla_ (greenish-white) _with nearly erect lobes, the tube not longer than the lanceolate divisions of the calyx_.--Moist grounds and banks of streams; common. Very variable. July, Aug.

ORDER 67. ASCLEPIADaCEae. (MILKWEED FAMILY.)

_Plants with milky juice, and opposite or whorled (rarely scattered) entire leaves; the follicular pods, seeds, anthers (connected with the stigma), sensible properties, etc., just as in the last family, from which they differ in the commonly valvate corolla, and in the singular connection of the anthers with the stigma, the cohesion of the pollen into wax-like or granular ma.s.ses_ (pollinia), etc., as explained under the typical genus Asclepias.

PERiPLOCA GRae'CA, L., a woody climbing plant of the Old World, in ornamental cultivation, and in one or two places inclined to be spontaneous, represents a tribe with granulose pollen loosely aggregated in two ma.s.ses in each anther-cell. It has a brownish rotate corolla, very hairy within, and with 5 awned scales in the throat.

Tribe I. CYNANCHEae. Anthers tipped with an inflexed or sometimes erect scarious membrane, the cells lower than the top of the stigma; pollinia suspended.

[*] Stems erect or merely dec.u.mbent.

1. Asclepiodora. Corolla rotate, merely spreading. Crown of 5 hooded fleshy bodies, with a salient crest in each. Leaves alternate.

2. Asclepias. Corolla reflexed, deeply 5-parted. Crown as in n. 1, but with an incurved horn rising from the cavity of each hood. Leaves usually opposite.

3. Acerates. Corolla reflexed or merely spreading. Crown as in n. 1, but with neither crest nor horn inside. Leaves mainly alternate.

[*][*] Stems twining. Leaves mostly opposite.

4. Enslenia. Corolla erect. Crown of 5 membranaceous flat bodies, terminated by a 2-cleft tail or awn.

5. Vincetoxic.u.m. Corolla rotate, spreading. Crown a fleshy 5--10-lobed ring or disk.

Tribe II. GONOLOBEae. Anthers with short if any scarious tip, borne on the margin of or close under the disk of the stigma; pollinia horizontal.

6. Gonolobus. Corolla rotate. Crown a wavy-lobed fleshy ring. Stems twining.

1. ASCLEPIODRA, Gray.

Nearly as in Asclepias, but the corolla-lobes ascending or spreading, and the hoods dest.i.tute of a horn, widely spreading and somewhat incurved, slipper-shaped and laterally compressed, the cavity divided at the apex by a crest-like part.i.tion.--Umbels solitary and terminal or corymbed, loosely-flowered. Follicles oblong or ovate, often somewhat muricate with soft spinous projections. (?s???p??? and d???? or d??e?, _the gift of aesculapius_.)

1. A. viridis, Gray. Almost glabrous; stems short (1 high); leaves alternate, short-petioled, ovate-oblong to lanceolate, 1--2' wide; umbels several in a cl.u.s.ter, short-peduncled; flowers large (1' in diameter), green, with a purplish crown. (Acerates paniculata, _Decaisne_.)--Prairies, Ill. to Tex. and S. Car. June.

2. ASCLePIAS, L. MILKWEED. SILKWEED.

Calyx 5-parted, persistent; the divisions small, reflexed. Corolla deeply 5-parted, the divisions valvate in the bud, reflexed, deciduous.

_Crown_ of 5 hooded bodies seated on the tube of stamens, each containing an incurved horn. Stamens 5, inserted on the base of the corolla; filaments united in a tube which encloses the pistil, anthers adherent to the stigma, each with 2 vertical cells, tipped with a membranaceous appendage, each cell containing a flattened pear-shaped and waxy pollen-ma.s.s; the two contiguous pollen-ma.s.ses of adjacent anthers, forming pairs which hang by a slender prolongation of their summits from 5 cloven glands that grow on the angles of the stigma (extricated from the cells by insects, and directing copious pollen-tubes into the point where the stigma joins the apex of the style). Ovaries 2, tapering into very short styles; the large depressed 5-angled fleshy stigmatic disk common to the two. Follicles 2, one of them often abortive, soft, ovate or lanceolate. Seeds anatropous, flat, margined, bearing a tuft of long silky hairs (_coma_) at the hilum, downwardly imbricated all over the large placenta, which separates from the suture at maturity. Embryo large, with broad foliaceous cotyledons in thin alb.u.men.--Perennial upright herbs, with thick and deep roots; peduncles terminal or lateral and between the usually opposite petioles, bearing simple many-flowered umbels, in summer. (The Greek name of _aesculapius_, to whom the genus is dedicated.)

-- 1. _Corneous anther-wings broadest and usually angulate-truncate and salient at base; horn conspicuous._

[*] _Flowers orange-color; leaves mostly scattered; juice not milky._

1. A. tubersa, L. (b.u.t.tERFLY-WEED. PLEURISY-ROOT.) Roughish-hairy (1--2 high); stems erect or ascending, very leafy, branching at the summit, and bearing usually numerous umbels in a terminal corymb; leaves from linear to oblong-lanceolate, sessile or slightly petioled; divisions of the corolla oblong (greenish-orange); hoods narrowly oblong, bright orange, scarcely longer than the nearly erect and slender awl-shaped horns; pods h.o.a.ry, erect on deflexed pedicels.--Dry fields, common, especially southward.--Var. DEc.u.mBENS, Pursh. Stems reclining; leaves broader and more commonly opposite, and umbels from most of the upper axils.--Ohio to Ga., etc.

[*][*] _Corolla bright red or purple; follicles naked, fusiform, erect on the deflexed pedicels_ (except in n. 5); _leaves opposite, mostly broad_.

[+] _Flowers rather large; hoods about 3" long and exceeding the anthers; leaves transversely veined._

2. A. paupercula, Michx. Glabrous; stem slender (2--4 high); leaves elongated-lanceolate or linear (5--10' long), tapering to both ends, slightly petioled, _umbels 5--12-flowered_; divisions of the red corolla narrowly oblong; the _bright orange hoods_ broadly oblong, obtuse, much exceeding the incurved horn.--Wet pine-barrens on the coast, N. J. to Fla. and Tex.

3. A. rubra, L. _Glabrous; leaves ovate or lanceolate and tapering from a rounded or heart-shaped base_ to a very acute point, sessile or nearly so (2--6' long, --2' wide), bright green; umbels many-flowered; divisions of the corolla and hoods _oblong-lanceolate, purple-red; the horn long and slender, straightish_.--Wet pine-barrens, etc., N. J. and Penn. to Fla., La., and Mo.

4. A. purpurascens, L. (PURPLE M.) Stem rather slender (1--3 high); _leaves elliptical or ovate-oblong_, the upper taper-pointed, _minutely velvety-downy underneath_, smooth above, _contracted at base into a short petiole; pedicels_ shorter than the peduncle, _3--4 times the length of the dark purple lanceolate-ovate divisions of the corolla_; hoods oblong, abruptly narrowed above; _the horn broadly scythe-shaped, with a narrow and abruptly inflexed horizontal point_.--Dry ground, N. Eng. to Minn., Tenn., and southward.--Flowers 6" long.

[+][+] _Flowers small; hoods 1" long, equalling the anthers; veins ascending._

5. A. incarnata, L. (SWAMP MILKWEED.) Smooth, or nearly so, in the typical form, the stem with two downy lines above and on the branches of the peduncles (2--3 high), very leafy; leaves oblong-lanceolate, acute or pointed, obtuse or obscurely heart-shaped at base; flowers rose-purple; hoods scarcely equalling the slender needle-pointed horn.--Swamps, common.--Var. PuLCHRA, Pers.; leaves broader and shorter-petioled, more or less hairy-p.u.b.escent, as well as the stem.

Milky juice scanty.--With the smooth form.

[*][*][*] _Flowers greenish, yellowish, white, or merely purplish-tinged; leaves opposite or whorled, or the upper rarely scattered._

[+] _Follicles echinate with soft spinous processes, densely tomentose (smooth, and only minutely echinate at the apex in n. 8), large (3--5'

long), ovate and ac.u.minate, erect on deflexed pedicels; leaves large and broad, short-petioled; umbels terminal and lateral._

6. A. specisa, Torr. Finely canescent-tomentose or glabrate, _the many-flowered umbel and calyx densely tomentose_; leaves _subcordate-oval_ to oblong; corolla-lobes purplish, ovate-oblong, 4--5" long; hoods 5--6" long, with a short inflexed horn, _the truncate summit abruptly produced into a very long lanceolate-ligulate appendage_.--Along streams, Minn. to Ark., and westward.

7. A. Cornuti, Decaisne. (COMMON MILKWEED or SILKWEED.) Stem tall and stout, finely soft-p.u.b.escent; _leaves_ oval-oblong (4--8' long), pale, _minutely downy beneath, as well as the peduncles_, etc.; corolla-lobes dull purple to white, 3--4" long; _hoods_ rather longer than the anthers, _ovate, obtuse, with a tooth each side of the short stout claw-like horn_.--Rich ground, everywhere.