Wild Flowers of Pittsburgh

Apocynaceae

Common Milkweed (Asclepias syriaca)

This distinctively odd-looking plant is a common sight along the road or at the edges of fields; this one grew at the edge of a field near Cranberry, where it was blooming in late June. The plants stand straight and tall; the flowers form umbels in almost perfect spheres. From a distance their color resembles the color that used to be called “flesh” in children’s crayon boxes, although some plants—like this one—bear flowers closer to white. The strong scent is irresistible to butterflies.

Milkweeds and their allies were traditionally placed in the Milkweed family, Asclepiaceae; but modern botanists make that family a subfamily (Asclepiadoideae) of the Dogbane family, Apocynaceae. The species name syriaca comes from a pre-Linnaean botanist who confused this species with one from the Near East.

Another picture is here.

Gray describes the genus and the species:

ASCLEPIAS [Tourn.] L. MILKWEED. SILKWEED. Calyx persistent; divisions small, reflexed. Corolla deeply 5-parted; divisions valvate in bud, 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 into a tube which incloses the pistil; anthers adherent to the stigma, each with 2 vertical cells, tipped with a membranaeeons appendage, each cell containing a flattened pear-shaped and waxy pollen-mass; the two contiguous pollen-masses 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, ovoid 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 albumen. Perennial herbs; 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.)

A. syriaca L. (COMMON M. or SILKWEED.) Stem tall and stout, finely soft-pubescent; leaves lance-oblong to broadly oval, 1-2 dm. long, pale, minutely downy beneath, as well as the peduncles, etc.; corolla-lobes dull purple to white, 6-9 mm. long; hoods rather longer than the anthers, ovate, obtuse, with a tooth each side of the short stout claw-like horn. (A. Cornuti Dene.) Rich ground, N. B. to Sask., and southw. June-Aug. Intermediates, perhaps of hybrid origin, occur between this and some of the related species.

Periwinkle (Vinca minor)

This ornamental ground cover has made itself at home all over the city. It persists indefinitely once it establishes itself, and spreads in shady areas too dim for other flowers. It also goes by the common names Myrtle and Cemetery Vine—the latter because its sober habits, dark leaves, and general indestructibility made it a favorite planting at cemeteries. This patch grew in the woods in West End Park, where it was blooming in the middle of April.

Gray describes the genus and the species:

VÍNCA L. PERIWINKLE.. Calyx-lobes acuminate. Corolla-tube funnel-form; the limb salver-form. Stamens inserted below the throat; filaments short. Style slender. Pods short-cylindric. Seeds rough. —Smooth trailing hardy plants (or in the Tropics tender annuals) with evergreen firm leaves and axillary flowers. (Ancient Latin name of uncertain derivation.)

V. minor L. (COMMON P., “MYRTLE.”) Spreading by creeping stems; leaves glossy, ovate to oblong, 1.5-3 cm. long, flowers peduncled; corolla blue, with truncate lobes. —Roadsides, etc., escaped from cultivation. Apr.-Juue. (Introd. from Eu.)


Indian Hemp (Apocynum cannabinum)

A tidy plant easily mistaken for a small shrub, especially when it grows a the edge of the woods with the rest of the undergrowth. It belongs to the same family that gives us our garden periwinkles. The red stem and smooth, elliptical leaves give the plant an elegant appearance, and the little flowers look as though they were made from the finest porcelain. The plant is poisonous, however; the name “dogbane” attaches itself to the whole family for good reason. This plant was growing by a tombstone in an overgrown cemetery in Beechview, where it was blooming in the middle of July.

The distinctive long seedpods look a bit like string beans, as we see on another plant that grew by the edge of the woods in the same cemetery.

Gray describes the genus and the species:

APÓCYNUM [Tourn.] L. DOGBANE. INDIAN HEMP. Calyx-lobes acute. Corolla bell-shaped, bearing 5 triangular appendages below the throat opposite the lobes. Stamens on the very base of the corolla; filaments shorter than the arrow-shaped convergent anthers, which slightly adhere to the stigma. Style none; stigma large, ovoid, slightly 2-lobed. Fruit of 2 long and slender follicles. Seeds with a tuft of long silky down at the apex. — Perennial herbs, with upright branching stems, opposite mucronatepointcd leaves, a tough fibrous bark, and small and pale cymose flowers on short pedicels. (Ancient name of the Dogbane, composed of apo, from, and kyona dog.)

* * Corolla greenish to greenish-white, tubular, pentagonal, 3-4.5 mm. long, the lobes ascending; cymes terminal, of mostly ascending flowers.

A. cannábinum L. (INDIAN HEMP.) Glabrous, 2-24 dm. high, the stems and branches ascending (but on gravel beaches, etc., depressed and wide-spreading), leaves mostly ascending, usually pale green, ovate-oblong to lanceolate, glabrous or sparingly pubescent beneath, those of the chief axis narrowed at base to distinct petioles (2-7 mm. long), those of the branches often subsessüe: central cyme flowering first; flowers erect; calyx glabrous, its lobes about equaling the corolla, tube. — Gravelly or sandy soil, mostly near streams; on beaches becoming dwarfed and diffuse, with smaller and narrower leaves (A. album Greene). June-Aug.

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In Wild Flowers East of the Rockies (1910), Chester Albert Reed does not share our opinion of the elegance of this plant; but he does give us a good description and some of the history of it:

INDIAN HEMP (Apocynum cannabinum) is a rather unattractive species with a smooth branching stem, rising from vertical roots to heights of 1 to 4 feet. The ovate-pointed leaves are lusterless, have very short stems and are closely crowded on the stalk oppositely to one another.

The small, five-parted, greenish-white flowers grow in terminal clusters. A tiny drop of nectar, secreted at the bottom of each small, shallow cup, furnishes food for quantities of insects, including a great many crawling ones that are of no value to the plant. The name of Indian Hemp has its origin because Indians formerly used the tough fibres as a substitute for hemp in their basket work. We find this species very abundant in dry fields and thickets throughout our range; it flowers from June to August.


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