Flora Pittsburghensis

Author: Father Pitt

  • Broadleaf Toothwort (Cardamine diphylla)

    Not as common around here as its close relative the Cutleaf Toothwort (Cardamine concatenata), this plant grows on the same wooded hillsides, especially in stream valleys. It’s easily distinguished by its two leaves with three broad leaflets each (C. concatenata has three leaves with very narrow lobes). This plant was blooming in early May near the Trillium Trail in Fox Chapel.

    Gray lists this as Dentaria diphylla. He describes the genus and the species thus:

    DENTARIA [Tourn.] L. TOOTHWORT. PEPPER-ROOT
    Pod lanceolate, flat. Style elongated. Seeds in one row, wingless, the funiculus broad and flat. Cotyledons petioled, thick, very unequal, their margins somewhat infolding each other. —Perennials, of damp woodlands, with long fleshy sometimes interrupted scaly or toothed rootstocks, of a pleasant pungent taste; steins leafless below, bearing 2 or 3 petioled compound leaves about or above the middle, and terminated by a corymb or short raceme of large white or purple flowers. (Name from dens, a tooth.)

    D. diphylla Michx. Rootstock long and continuous, often branched, the annual segments slightly or not at all tapering at the ends; stems in anthesis 1.5-3 dm. high, stoutish; leaves 3-foliolate, the basal and cauline similar, the latter 2 (rarely 3), opposite or subopposite, leaflets 4-10 cm. long, short-petiolulate, rhombic-ovate or oblong-ovate, coarsely crenate, the teeth bluntly mucronate; flowers white; sepals 5-8 mm. long, half the length of the petals; pods rarely maturing. Rich woods and thickets, e. Que. to s. Ont. and Minn., s. to S.C. and Ky. Apr., May. Rootstocks 2-3 dm. long, crisp, tasting like Water Cress.

  • 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. )

  • Watercress (Nasturtium officinale)

    Nasturtium-officinale-2009-10-22-Wexford-01

    Watercress likes to grow with its feet in the edge of a lazy stream. This colony grew in a little tributary of the Pine Creek in Wexford, where it was blooming profusely in late October. The main blooming season is in the spring, but the cool weather of fall seems to give the plants their second wind.

    Gray lists the plant as Radicula nasturtium-aquaticum:

    RADICULA [Dill.] Hill. WATER CRESS
    Pod a short silique or a silicle, varying from slender to globular, terete or nearly so; valves strongly convex, nerveless. Seeds usually numerous, small, turgid, marginless, in 2 irregular rows in each cell (except in R. sylvestris).  Cotyledons accumbent. Aquatic or marsh plants, with yellow or white flowers, and commonly pinnate or pinnatifid leaves, usually glabrous. (Name meaning a little radish.)  RORIPA Scop.   NASTURTIUM R. Br.

    1. Petals white, twice the length of the calyx, pods linear; leaves pinnate.

    R. NASTURTIUM-AQUATICUM (L.) Britten & Rendle. (TRUE W.) Perennial; stems spreading and rooting; leaflets 3-11, roundish or oblong, nearly entire; pods (1.2-1.6 cm. long) ascending on slender widely spreading pedicels. (Sisymbrium L.; Nasturtium officinale R. Br.; Roripa Nasturtium Rusby.)—Brooks, ditches, etc., originally cultivated. (Nat. from Eu.)