Flora Pittsburghensis

Category: Compositae

  • New England Aster (Symphyotrichum novae-angliae), Pink Form

    Photographed September 15.

    The American members of the genus Aster have been moved to the genus Symphyotrichum, and we hope they like it there. This is our showiest Aster, and the pink form is fairly rare; Gray would make it var. roseus (which, in the neuter genus Symphyotrichum instead of the masculine Aster, would be var. roseum). We also have pictures of the usual purple form and the very rare white form.

    Gray describes the genus Aster (where all North American species of Symphyotrichum lived until recently) and the species:

    ASTER [Tourn.] L. STAR-WORT, FROST-FLOWER, ASTER. Heads many-flowered, radiate; the ray-flowers in a single series, fertile. Bracts of the involucre more or less imbricated, usually with herbaceous or leaf-like tips. Receptacle flat, alveolate. Achenes more or less flattened; pappus simple, of capillary bristles (double in 4 and 5). Perennial herbs (annual only in 7 and 8), with corymbed, panicled, or racemose heads, flowering chiefly in autumn. Rays white, purple, blue, or pink; the disk yellow, often changing to purple. Species often without sharply defined limits, freely hybridizing. (Name aster, a star, from the radiate heads of flowers.)

    A. nòvae-ángliae L. Stem stout, hairy, 0.5-2.6 m. high, corymbed at the summit; leaves numerous, lanceolate, entire, acute, auriculate-clasping, 930. A. oblongifolius. clothed with minute pubescence, 0.5- 1 dm. long; bracts nearly equal, linear-awl-shaped, loose, glandular-viscid, as well as the branchlets; rays violet-purple, rarely white, very numerous; achenes hairy. Moist chiefly calcareous grounds, centr. Me. to w. Que., westw. and south w. Aug.-Oct. Heads large ; a very handsome species, popular in cultivation. (Escaped from gardens, and locally naturalized in Eu.) FIG. 931. Var. róseus (Desf.) DC. Rays pink or rose-color. Range of the typical form, local.

  • Bur-Marigold (Bidens frondosa)

    Photographed September 15.

    More often these plants have no rays on their flower heads, but forms with rays do occur, and this patch growing in Bird Park (Mount Lebanon) had unusually abundant rays on some flower heads (none on others). The “bur” in the name is the seed, which has a pair of little spikes that attach it to fur or clothing, spreading the plant very efficiently. It is distinguished from Spanish Needles (Bidens bipinnata) by larger flower heads with more florets, and by its leaves with three or five leaflets. The stems are often reddish.

    Gray describes the genus and the species:

    BÌDENS L. BUR MARIGOLD. Heads many-flowered; the rays when present 3-8, neutral. Involucre double, the outer commonly large and foliaceous. Receptacle flattish; chaff deciduous with the fruit. Achenes flattened parallel to the bracts of the involucre, or slender and 4-sided (rarely terete), crowned with awns or short teeth (these rarely naked). — Annual or perennial herbs, with opposite various leaves, and mostly yellow flowers. (Latin, bidens, two-toothed.)

    N. B. — In this genus the measurements of the fruit relate to the inner mature achenes. The outer are often shorter and uncharacteristic.

    B. frondòsa L. (BEGGAR-TICKS.) Stems tall (7 dm. or less in height), paniculate-branched; leaves 3–5-divided, glabrous, the terminal leaflet long-stalked, acuminate, often again divided, lateral ones shorter, less acuminate, all sharply serrate; heads 1.5 cm. long or less, on slender peduncles; outer involucre of 5–8 ciliate bracts; rays small, yellow; achenes narrowly cuneate, 7-10 mm. long, black, strongly 1-nerved on each face, often slightly hairy, the retrorsely barbed slightly divergent slender awns barely half as long, exceeding the 5-toothed orange corolla. (B. melanocarpa Wiegand.) — Common in damp ground, throughout. Aug., Sept. Fig. 994. Var. ANOMALA Porter. Awns upwardly barbed. — Local, N. S. to Pa.

  • Tall Thoroughwort (Eupatorium altissimum)

    Eupatorium altissimum

    Long stands of this dusty white thoroughwort line our highways. The narrow grey-green three-ribbed leaves (sometimes there are five ribs) are distinctive, and the mounds of white flowers are very attractive to honeybees. “All specimens in the Herbarium were collected recently,” says the 1951 Check List of the Vascular Flora of Allegheny County. “This is a Mississippi Valley species, entering the State from the southwest, particularly along the river bluffs.” Since then, the plant has become very much at home here, but it is still found mostly along the highways and railroads by which it entered.

    This is a very common species here, but oddly underrepresented in photographs. As usual, Father Pitt donated these pictures to Wikimedia Commons, and these half-dozen photographs exactly doubled the collection for this species.

    Gray describes the genus and the species:

    EUPATORIUM [Tourn.] L. THOROUGHWORT. Heads discoid, 3-many-flowered; flowers perfect. Involucre cylindrical or bell-shaped, of more than 4 bracts. Receptacle flat or conical, naked. Corolla 5-toothed. Achenes 5-angled; pappus a single row of slender capillary barely roughish bristles. Erect perennial herbs, often sprinkled with bitter resinous dots, with generally corymbose heads of white, bluish, or purple blossoms, appearing near the close of summer. (Dedicated to Eupator Mithridates, who is said to have used a species of the genus in medicine.)

    Heads 3-20-flowered; involucre of 8-15 more or less imbricated and unequal bracts, the outer ones shorter; flowers white or nearly so.

    Leaves sessile or nearly so, with a narrow base, mostly opposite; heads mostly 5-flowered.

    Bracts not scarious or only obscurely so, obtuse, at length shorter than the flowers.

    E. altissimum L. Stem stout and tall, 1-2 m. high, downy leaves lanceolate, tapering at both ends, conspicuously 3-nerved, entire, or toothed above the middle, 0.5-1.3 dm. long, the uppermost alternate; corymbs dense; bracts of the involucre obtuse, shorter than the flowers. Dry soil, Pa. to Minn., Neb., and southw.

  • Zigzag Goldenrod (Solidago flexicaulis)

    Photographed September 10.

    A distinctive goldenrod that likes clearings in the woods or the banks of a stream. Its broad rounded toothy leaves are distinctive, and it takes its common name from the angled stems, which zigzag from one leaf to the next. (“Zigzag” is a technical term in botany.) The flowers grow in a wand at the top of the stem, with more flowers filling in the leaf axils.

    Gray gives us a description of the genus Solidago:

    SOLIDAGO L. GOLDEN-ROD. Heads few-many-flowered, radiate; the rays 1-16, pistillate. Bracts of the involucre appressed, destitute of herbaceous tips (except nos. 1 and 2). Receptacle small, not chaffy. Achenes many-ribbed, nearly terete; pappus simple, of equal capillary bristles. —Perennial herbs, with mostly wand-like stems and sessile or nearly sessile never heart-shaped stem-leaves. Heads small, racemed or clustered; flowers both of the disk and ray yellow (cream-color in no. 6). Closely related species tending to hybridize freely. (Name from solidare, to join, or make whole, in allusion to reputed vulnerary qualities.)

    Gray makes this species part of Solidago latifolia, so we turn to Britton for a description of the species according to current taxonomy (note his use of the technical botanical term we mentioned above):

    Solidago flexicaulis L. ZIG-ZAG OR BROAD-LEAVED GOLDENROD. Stem glabrous, angled, usually simple, zig-zag, 3-9 dm. high. Leaves thin, ovate, acuminate at the apex, somewhat pubescent, or glabrous beneath, sharply serrate, 5-17 cm. long, 2-10 cm. wide, the uppermost sometimes lanceolate and entire or nearly so; heads about 6 mm. high; bracts of the involucre obtuse to acutish; achenes hirsute-pubescent. In rich woods, N. B. to Ga., west to S. Dak. and Kans. July-Sept.

  • Tall Ironweed (Vernonia gigantea)

    It is no secret that the ironweeds are among Father Pitt’s favorite flowers. When we take a close look at the flowers, we can see that the impression of extraordinarily vivid purple is partly created by adding some bright orange and white.