. Botany for secondary schools; a guide to the knowledge of the vegetation of the neighborhood. Plants. KNOTWEED FAMILY 351 4. POLYGONUM. Knotweed. Smahtweed. Low weedy plants, or some exotic ones tall and cultivated, blooming in summer and fall, the small pinkish or greenish flowers mostly in racemes or spikes (in the Knotweeds in the leaf-axils): calyx usually 5-parted: stamens 4-9: stigmas 2 or 3: black achene lenticular or triangular. a. Knotweeds: /lowers sessile in the axils of the leaves, greenish and very small. P. aviculare, Linn. Common knotweed. Doorweed. Fig. 210. Pros- trate or cr
. Botany for secondary schools; a guide to the knowledge of the vegetation of the neighborhood. Plants. KNOTWEED FAMILY 351 4. POLYGONUM. Knotweed. Smahtweed. Low weedy plants, or some exotic ones tall and cultivated, blooming in summer and fall, the small pinkish or greenish flowers mostly in racemes or spikes (in the Knotweeds in the leaf-axils): calyx usually 5-parted: stamens 4-9: stigmas 2 or 3: black achene lenticular or triangular. a. Knotweeds: /lowers sessile in the axils of the leaves, greenish and very small. P. aviculare, Linn. Common knotweed. Doorweed. Fig. 210. Pros- trate or creeping, bluish green wiry plant, growing along the hard edges of walks and in yards, and commonly mistaken for sod: leaves small, mostly oblong, entire: sepals very small, green with a broad white margin: stamens 5 or more: stigmas usually 3. Annual. P. erectum, Linn. Taller knotweed. One ft. or more high: leaves three or four times larger, oblong or oval and obtuse. Common annual. aa. Smarhveeds: flowers in terminal spikes, mostly pinkish. b. Sheaths of leaves (surrounding stem) hairy on the edge, or the margin with a spreading border. P. orientate, Linn. Prince's feather. Several feet tall, soft- hairy: flowers in long cylindrical nodding spikes: leaves ovate: stamens 7. India; cultivated. Annual. P. Persicaria, Linn. Smartweed. Lady's thumb (from the dark blotch near the center of the leaf). Fig. 514. About 1 ft.: leaves lanceolate: spikes oblong, dense and erect: stamens usually 6: stigmas 2. Weed from Europe. P. Hydropiper, Linn. Smartweed. Herbage very pungent or "smarty:" leaves oblong-lanceolate: spikes short and nodding, the flowers greenish: stamens 6: stigmas 3. Low grounds. Annual. P. hydropiperoides, Michx. Smartweed. Herbage not pungent: spikes slender and erect, the flowers whitish: sta- mens 8: stigmas 3. In very wet places. Perennial. P. acre, HBK. Smartweed. Herbage pungent: leaves linear or lanceolate, long-pointed: spikes slender and erect: flowers
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