Category: Compositae

  • Sow Thistle (Sonchus oleraceus)

    Nasty prickly weeds that they are, the Sow Thistles have a certain architectural elegance. The buds are shaped like a fine glass vase, and the clasping leaves are a particulary attractive dark green. Sow Thistles are edible, apparently, if you catch them young or don’t mind sticking sharp things in your mouth. This one was blooming beside a telephone pole in Beechview in early November.

    Gray describes the genus and the species:

    SONCHUS [Tourn.] L. SOW THISTLE.
    Heads many-flowered, becoming tumid at base. Involucre more or less imbricated. Achenes obcompressed, ribbed or striate, not beake; pappus copious, of very white exceedingly soft and fine bristles mainly falling together. Leafy -stemmed coarse weeds, chiefly smooth and glaucous, with corymbed or umbellate heads of yellow flowers produced in summer and autumn. (The ancient Greek name.)

    Annual; flowers pale yellow.

    S. OLERACEUS L. (COMMON S.) Stem-leaves runcinate-pinnatifid, rarely undivided, slightly toothed with soft spiny teeth, clasping by a heart-shaped base, the auricles acute; involucre downy when young; achenes striate, also wrinkled transversely. Waste places, chiefly in manured soil and around dwellings. (Nat. from Eu.)

  • Woodland Sunflower (Helianthus divaricatus)

    Normally a late-summer flower, but this one was gamely blooming in early November after more than one frost, when perennial sunflowers are supposed to be settling in for the winter. It likes shade, and is happiest at the edge of a woodland clearing; this one was growing along a thickly wooded street in Beechview. Note the opposite lanceolate leaves with shallow teeth and the slightly sloppy downward-facing pointed bracts.

    Gray describes the genus and the species:

    HELIANTHUS L. SUNFLOWER
    Heads many-flowered; rays several or many, neutral. Involucre imbricated, herbaceous or foliaceous. Receptacle flat or convex; the persistent chaff embracing the 4-sided and laterally compressed smooth achenes, which are neither winged nor margined. Pappus very deciduous, of 2 thin chaffy scales on the principal angles, and sometimes 2 or more small intermediate scales. —Coarse and stout herbs, with solitary or corymbed heads, and yellow rays; flowering toward autumn. (Named from helios, the sun, and anthos, a flower.)

    H. divaricatus L. Stem simple or forked and corymbed at the top, 0.5-2 m. high, smooth below; leaves all opposite and divaricate, ovate-lanceolate, 3-nerved from the rounded or truncate sessile base, tapering gradually to a sharp point, 0.5-2 dm. long, serrate, thickish, rough both sides; bracts narrowly lanceolate, attenuate, ciliate, equaling the disk (1 cm. wide); rays 8-12, 2.5 cm. long. Thickets and barrens, s. Me. to L. Winnipeg, Neb., and southw.

  • Zigzag Aster (Aster prenanthoides)

    Now Symphyotrichum prenanthoides. Blue asters are among the last flowers of the fall. Identifying asters is, of course, a foolish endeavor, but this one has the clasping leaves and zigzag stem that identify a Zigzag Aster. It was blooming at the edge of the woods near the parking lot of the Pittsburgh Zoo in late October.

    From Gray’s Manual:

    A. prenanthoides Muhl. Stem 1 m. or less high, corymbose-panicled, hairy above in lines; leaves rough above, smooth underneath, ovate to lanceolate, sharply cut-toothed in the middle, conspicuously taper-pointed, and rather abruptly narrowed to a long contracted entire portion, which is abruptly dilated into a conspicuously auricled base; heads on short divergent peduncles; involucre 5-8 mm. high; bracts narrowly linear, tips recurved-spreading; rays violet. Borders of streams and rich woods, w. N. E. to Va. and Ky., w. Minn, and Ia. Aug.-Oct.

  • Late Thoroughwort (Eupatorium serotinum)

    Eupatorium-serotinum-2009-10-24-Oakmont

    Some of the Late Thoroughworts are stlil blooming as October fades into November. They can hybridize with other members of the genus Eupatorium, but this one appears to be a pure strain—note the smooth leaves, with petioles and without teeth, which set this species apart from either Boneset (Eupatorium perfoliatum) or White Snakeroot (Eupatorium rugosum). It was blooming in late October along a seldom-used railroad siding in Oakmont.

    From Gray’s Manual of Botany: Eupatorium serotinum Michx. Stem pulverulent-pubescent, bushy-branched, 1-2 m. high; leaves ovate-lanceolate, tapering to a point, triple-nerved and veiny, coarsely serrate, 0.5-1.5 dm. long; involucre very pubescent. Alluvial ground, Md. to Minn., e. Kan., and south w.

  • Canada Thistle (Cirsium arvense)

    Cirsium-arvense-2009-10-24-Oakmont

    This would certainly be one of our most prized ornamentals if it weren’t prickly, ubiquitous, and ineradicable. The seeds are prized by goldfinches, which are among our most ornamental birds. This plant was blooming in late October along a seldom-used railroad siding in Oakmont.

    Gray describes the genus and the species:

    CIRSIUM [Tourn.] Hill. COMMON or PLUMED THISTLE

    Heads many-flowered; flowers all tubular, perfect and similar, rarely imperfectly dioecious. Bracts of the ovoid or spherical involucre imbricated in many rows, tipped with a point or prickle. Receptacle thickly clothed with soft bristles or hairs. Achenes oblong, flattish, not ribbed; pappus of numerous bristles united into a ring at the base, plumose to the middle, deciduous. Herbs, mostly biennial; the sessile alternate leaves often pinnatifid, prickly. Heads usually large, terminal. Flowers reddish-purple, rarely white or yellowish; in summer. (Name from kirsos, a swelled vein, for which the Thistle was a reputed remedy.) CNICUS of many auth., not L. By some recent Am. auth. included in CARDUUS.

    * * * * Outer bracts of the appressed involucre barely prickly-pointed; heads mostly small and numerous. None of the leaves strongly decurrent.

    13. C. ARVENSE (L.) Scop. (CANADA THISTLE.) Perennial, slender, 3-9 dm. high, the rootstock extensively creeping; leaves oblong or lanceolate, smooth, or slightly woolly beneath, finally green both sides, strongly sinuate-pinnatifid, very prickly-margined, the upper sessile hut smrrcly decurrent; heads imperfectly dioecious; flowers rose-purple or whitish. (Carduus Robson; Cnicus Hoffm.) Cultivated fields, pastures, and roadsides, common; a most troublesome weed, extremely difficult to eradicate. (Nat. from Eu.) Var. VEST!TUM Wimm. & Grab. Leaves permanently white-lanate beneath. Locally established. (Nat. from Eu.) Var. INTEGRIFOLIUM Wimm. & Grab. Leaves  chiefly plane and uncut, or the lowest slightly pinnatifid. Local, Que., N. E., and N. Y. (Nat. from Eu. )