1. P. pùmila, Gray. (Richweed. Clearweed.) Low (3–18´ high); stems smooth and shining, pellucid; leaves ovate, coarsely toothed, pointed, 3-ribbed and veiny; flower-clusters much shorter than the petioles; sepals of the fertile flowers lanceolate, scarcely unequal.—Cool and moist shaded places. July–Sept.
11. BŒHMÈRIA, Jacq. False Nettle.
Flowers monœcious or diœcious, clustered; the sterile much as in Urtica; the fertile with a tubular or urn-shaped entire or 2–4-toothed calyx enclosing the ovary. Style elongated awl-shaped, stigmatic and papillose down one side. Achene elliptical, closely invested by the dry and persistent compressed calyx.—No stings. (Named after G. R. Boehmer, Professor at Wittenberg in the last century.)
1. B. cylíndrica, Willd. Perennial, smoothish or pubescent and more or less scabrous; stem (1–3° high) simple; leaves chiefly opposite (rarely all alternate), ovate to ovate- or oblong-lanceolate, pointed, serrate, 3-nerved; stipules distinct; petioles short or elongated; flowers diœcious, or the two kinds intermixed, the small clusters densely aggregated in simple and elongated axillary spikes, the sterile interrupted, the fertile often continuous, frequently leaf-bearing at the apex.—Moist or shady ground, common. Very variable.
12. PARIETÀRIA, Tourn. Pellitory.
Flowers monœciously polygamous; the staminate, pistillate, and perfect intermixed in the same involucrate-bracted cymose axillary clusters; the sterile much as in the last; the fertile with a tubular or bell-shaped 4-lobed and nerved calyx, enclosing the ovary and the ovoid achene. Style slender or none; stigma pencil-tufted.—Homely, diffuse or tufted herbs, not stinging, with alternate entire 3-ribbed leaves, and no stipules. (The ancient Latin name, because growing on old walls.)
1. P. Pennsylvánica, Muhl. Low, annual, simple or sparingly branched, minutely downy; leaves oblong-lanceolate, thin, veiny, roughish with opaque dots; flowers shorter than the involucre; stigma sessile.—Shaded rocky banks, E. Mass. and Vt. to Minn., and southward. June–Aug.
Order 100. PLATANÀCEÆ. (Plane-tree Family.)
Trees, with watery juice, alternate palmately-lobed leaves, sheathing stipules, and monœcious flowers in separate and naked spherical heads, destitute of calyx or corolla; the fruit merely club-shaped 1-seeded nutlets, furnished with a ring of bristly hairs about the base; consists only of the following genus (of uncertain relationship).
1. PLÁTANUS, L. Sycamore. Buttonwood.