Flora Pittsburghensis

Author: Father Pitt

  • Giant Knotweed (Fallopia sachalinensis)

    Also known as Sachalin. The lesser-known of two beautiful but pernicious Japanese invaders, Giant Knotweed closely resembles its cousin the Japanese Knotweed (F. japonica), but can be distinguished by the leaves, which are longer and pointier and have a heart-shaped base rather than the rounded base of F. japonica. Like the Japanese Knotweed, Giant Knotweed can form large colonies that completely exclude other species of vegetation. These plants grew in an old German cemetery in Beechview, where they were blooming in the middle of September.

    Because this imported weed was not so weedy in Gray’s time, we turn to the on-line Flora of North America at efloras.org:

    Fallopia Adanson, Fam. Pl. 2: 277, 557. 1763.
    [name conserved]

    False-buckwheat [for Gabriello Fallopio, 1532-1562, Italian anatomist] Craig C. Freeman, Harold R. Hinds. Bilderdykia Dumortier.

    Vines or herbs, annual or perennial; roots fibrous or woody; sometimes rhizomatous. Stems erect to scandent, rarely procumbent, glabrous or pubescent. Leaves deciduous, cauline, alternate, petiolate; ocrea persistent or deciduous, chartaceous; petiole base articulated, extrafloral nectaries sometimes present; blade broadly ovate to triangular, margins entire or wavy. Inflorescences terminal and spikelike, or terminal and axillary and paniclelike or racemelike, pedunculate or not. Pedicels present. Flowers bisexual, or bisexual and unisexual, some plants with bisexual flowers, other plants with only pistallate flowers 1-5 per ocreate fascicle, base stipelike; perianth usually accrescent in fruit, pale green or white to pink, campanulate, glabrous or, rarely, with blunt, hyaline hairs; tepals 5, connate nearly completely or only basally, petaloid, dimorphic, outer 3 winged or keeled, larger than inner 2; stamens 6-8; filaments distinct, free, glabrous or pubescent proximally; anthers yellow to pink or red, ovate to elliptic; styles 3, spreading, connate basally or nearly completely; stigmas capitate, fimbriate, or peltate. Achenes included or exserted, brown to dark brown or black, not winged, 3-gonous, glabrous. Seeds: embryo straight. x = 10, 11.

    Species ca. 12 (8 in the flora): North America (including Mexico), South America, Europe, Asia, Africa.

    Herbs, perennial, rhizomatous, 2-4(-5) m. Stems usually clustered, erect, sparingly branched, herbaceous, stiff, glabrous, glaucous. Leaves: ocrea persistent or deciduous, brownish, cylindric, 6-12 mm, margins oblique, face without reflexed and slender bristles at base, otherwise glabrous or puberulent; petiole 1-4 cm, glabrous; blade ovate-oblong, 15-30(-40) × 7-25 cm, base cordate, margins entire, glabrous or scabrous to ciliate, apex obtuse to acute, abaxial face minutely dotted, glaucous, with hairs along veins distinctly multicellular, 0.2-0.6 mm, tips acute to acuminate, adaxial face glabrous. Inflorescences axillary, mostly distal, erect or spreading, paniclelike, 3-8 cm, axes puberulent to pubescent; peduncle 0.1-4 cm or absent, puberulent to reddish-pubescent. Pedicels ascending or spreading, articulated proximal to middle, 2-4 mm, glabrous. Flowers bisexual or pistillate, 4-7 per ocreate fascicle; perianth accrescent in fruit, greenish, 4.5-6.5 mm including stipelike base, glabrous; tepals obovate to elliptic, apex obtuse to acute, outer 3 winged; stamens 6-8; filaments flattened proximally, glabrous; styles connate basally; stigmas fimbriate. Achenes included, brown, 2.8-4.5 × 1.1-1.8 mm, shiny, smooth; fruiting perianth glabrous, wings flat to undulate, 1.8-2.2 mm wide at maturity, decurrent on stipelike base to articulation, margins entire. 2n = 44, 66, 102, 132 (Japan, Korea).

    Flowering Jul-Oct. Disturbed places; 0-500 m; introduced; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Calif., Conn., Del., Idaho, Ill., Ky., La., Maine, Md., Mass., Mich., Mont., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., Tenn., Vt., Va., Wash., W.Va., Wis.; Asia (Japan); introduced in Europe.

    Fallopia sachalinensis was introduced as a soil binder and garden ornamental. Like F. japonica, it spreads aggressively and has been declared noxious in California, Oregon, and Washington. It hybridizes with F. japonica, yielding F. ×bohemica. The mid-stem inflorescences of F. sachalinensis usually are shorter than the subtending leaves.

  • Climbing False Buckwheat (Fallopia scandens)

    This ubiquitous vine looks a bit like a bindweed until it starts to bloom; then the characteristic clusters of tiny flowers of the knotweed clan reveal themselves. Like bindweeds, it likes to clamber over a fence or an arbor, or—as it did here—over the weeds and shrubbery at the edge of the woods. These vines were growing at the edge of an old cemetery in Beechview, where they were blooming in the middle of September.

    Older botanists placed this genus in the large and polymorphous genus Polygonum. Gray describes that genus, the section Tinaria in which he places this species, and the species itself:

    POLÝGONUM [Tourn ] L. KNOTWEED. Calyx 4-6(mostly 5)-parted; the divisions often petal-like, all erect in fruit, withering or persistent. Stamens 3-9. Styles or stigmas 2 or 3; achene accordingly lenticular or 3-angular. Embryo placed in a groove on the outside of the albumen and curved halfway around it; the radicle and usually the cotyledons slender. Pedicels jointed. — Ours all herbaceous, with fibrous roots (except in P. viviparum), flowering through late summer and early autumn. (Name composed of poly-, many, and gonu, knee, from the numerous joints.)

    § 6. TINIÀRIA Meisn. Twining (except dwarf var. of no. 29), unarmed; leaves ovate-heart-shaped; flowers in panicled racemes; outer calyx-lobes keeled or winged.

    P. scándens L. (CLIMBING FALSE BUCKWHEAT.) Perennial, smooth; sheaths naked; leaves heart-shaped or slightly halberd-shaped, pointed; racemes interrupted, leafy; the 3 outer calyx-lobes strongly keeled and in fruit broadly winged, 10-15 mm. long; the wings often crisped, subentire; achene smooth and shining, 4 mm. long. (P. dumetorum, var. Gray.) — Moist thickets, common except on our northern borders. —Twining 2-4 m. over bushes. (Japan.)

  • Tall Blue Lettuce (Lactuca biennis)

    “Tall” is just the word we were looking for to describe this plant, which grew to at least twelve feet (4 m) in a clearing in the woods in Beechview. It was blooming in the middle of September. This is indeed a close relative of the garden Lettuce (L.sativa). The generic name, an old Latin word from which the common name is derived, refers to the milky white sap.

    Gray describes the genus and the species, which he lists as L. spicata:

    LACTÙCA [Tourn.] L. LETTUCE. Heads several-many-flowered. Involucre cylindrical or in fruit conical; bracts imbricated in 2 or more sets of unequal lengths. Achenes contracted into a beak, which is dilated at the apex, bearing a copious and fugacious vегу soft capillary pappus, its bristles falling separately. — Leafy-stemmed herbs, with panicled heads; flowers of variable color, produced in summer and autumn. (The ancient name of the Lettuce, L. sativa L.; from lac, milk, in allusion to the milky juice.)

    § 3. MULGÈDIUM (Cass.) Gray. Achenes thickish, oblong, contracted into a short thick beak or neck; annual or biennial; flowers chiefly blue.

    Pappus tawny.

    L. spicàta (Lam.) Hitchc. Nearly smooth biennial, tall (1-3.6 m. high), very leafy; leaves irregularly pinnatifid, sometimes runcinate, coarsely toothed, the upper cauline sessile and auriculate, sometimes clasping; heads in a large and dense compound panicle; flowers bluish to cream-color; achene short-beaked. (L. leucophoea Gray. ) — Low grounds, rather common.

  • Peppermint (Mentha × piperita)

    Peppermint is apparently a hybrid between Spearmint (Mentha spicata) and Watermint (Mentha aquatica). If nothing else, the scent and flavor of the leaves are enough to identify the plant. It shows a strong preference for damp locations, although it will grow almost anywhere you plant it. It seldom produces viable seed, but it nevertheless makes a nuisance of itself in some parts of the country. Around here it is only an occasional tasty volunteer. This colony was growing in a wet depression beside a tributary of Wexford Run, where it was blooming in early September.

    Linnaeus described this plant as a species, M. piperita; the × in Mentha × piperita denotes that the universal judgment of modern botanists identifies it as a hybrid. Gray’s description:

    MÉNTHA [Tourn.] L. MINT. Calyx Ьеll-shaped or tubular, the 5 teeth equal or nearly so. Corolla with a short included tube, the upper lobe slightly broader, entire or notched. Stamens 4, equal, erect, distant. — Odorous perennial herbs; the small flowers mostly in close clusters, forming axillary capitate whorls, sometimes approximated in interrupted spikes, produced in summer, of two sorts as to the fertility of the stamens in most species. Corolla pale purple or whitish. Species mostly adventive or naturalized from Europe, with many hybrids. (Minthe of Theophrastus, from a Nymph of that name, fabled to have been changed Into Mint by Proserpine.)

    M. piperìta L. (PEPPERMINT.) Glabrous, very pungent-tasted; leaves ovate-oblong to oblong-lanceolate, acute, sharply serrate; spikes becoming loose; calyx glabrous below, the teeth hirsute. — Along brooks, frequent. (Nat. from Eu.)

  • Dodder (Cuscuta gronovii)

    A curious parasitic member of the Morning-Glory family. Dodder has no green coloring of its own because it has no chlorophyll; instead, a seedling must, within a few days of sprouting, attach itself to a suitable host plant, and begin to rob it of its sap.

    There are many species of Dodder around the world, but this one is (as far as we know) the only one found in the Pittsburgh area, which makes it hard to misidentify. The stringy orange stems and the unearthly waxy flower clusters are unique. These vines were blooming along a tributary of Wexford Run in early September.

    The genus Cuscuta usually makes its home in the family Convolvulaceae, the Morning-Glory Family; but it sometimes runs away from home and attempts to establish a household for itself as the family Cuscutaceae. Right now the botanical consensus seems to place it in Convolvulaceae.

    Gray describes the genus and the species:

    CÚSCUTA [Tourn.] L. DODDER. LOVE-VINE.

    Calyx 5(rarely 4)-cleft, or of 5 sepals. Corolla globular-urn-ehaped, bellshaped, or short-tubular, the spreading border 5(rarely 4)-cleft, imbricate. Stamens with a scale-like often fringed appendage at base. Ovary 2-celled, 4-ovuled; styles distinct, or rarely united. Capsule mostly 4-seeded. Embryo spirally coiled in the rather fleshy albumen, sometimes with a few alternate scales (belonging to the plumule); germination occurring in the soil. — Leafless annual herbs, with thread-like yellowish or reddish stems, bearing a few minute scales in place of leaves; on rising from the ground becoming entirely parasitic on the bark of herbs and shrubs on which they twine, and to which they adhere by means of suckers developed on the surface in contact. Flowers small, cymose-clustered, mostly white, usually produced in summer and autumn. (Name supposed to be of Arabic derivation.)

    Calyx gamosepalous; ovary and capsule pointed, the latter enveloped or capped by the marcescent corolla; flowers in loose panicled cymes.

    Corolla-lobes obtuse, spreading.

    C. gronòvii Willd. Stems coarse, often climbing high; corolla-lobes shorter than or equaling the deeply campanulate tube; scales copiously fringed; capsule globose, umbonate.— Wet shady places, N. S. to Man., and southw. — The commonest of our species. Very variable in size and compactness of clusters.