7. Amaranthus hybridus L. (green amaranth, slender pigweed)
Pl. 198 g, h;
Map 816
Plants
monoecious. Stems 30–200 cm long, erect or ascending, sparsely (toward the
base) to densely (toward the tip) pubescent with mostly crinkled, multicellular
hairs, unarmed. Leaves short- to long-petiolate. Leaf blades 2–15 cm long,
lanceolate to ovate or elliptic, narrowed or tapered to a bluntly or sharply
pointed tip (often minutely notched at the very tip), narrowed or tapered at
the base, the surfaces sparsely to moderately pubescent mostly along the veins
with inconspicuous, mostly crinkled, multicellular hairs, the upper surface
sometimes glabrous or nearly so. Inflorescences dull or grayish green,
occasionally dull reddish-tinged, axillary and terminal, the axillary
inflorescences short spikes or less commonly dense globose clusters, the
terminal inflorescence usually a panicle with numerous clusters of short, dense
spikes (these branching along most of the panicle axis), the flowers mostly
continuous along the spikes, the tip often curved or nodding, the main axis and
branches moderately to densely pubescent with mostly crinkled, multicellular
hairs. Bracts 2–4 mm long, the main body (excluding the awn) shorter than to
slightly longer than the fruits, but the entire structure (including the
awnlike or spinelike extension of the midrib) conspicuously longer than the
fruits, lanceolate to ovate, narrowed or tapered to a sharply pointed tip, with
a strongly thickened green midrib and narrow or broad, thin, papery margins,
the midrib usually extending beyond the main body as a short awn, spinelike at
maturity. Staminate flowers with (4)5 more or less similar sepals, these 1.5–2.3
mm long, straight, elliptic to oblong-ovate, narrowed or tapered to a sharply
pointed tip, usually tapered to a short, awnlike extension of the midrib.
Stamens (4)5. Pistillate flowers with (4)5 more or less similar sepals, these
1.5–2.3 mm long, straight or nearly so, lanceolate to oblong-elliptic or oblong-ovate,
narrowed or tapered to a relatively stiff, sharply pointed tip, often tapered
to a short, awnlike extension of the midrib. Stigmas 3, erect or less commonly
somewhat spreading. Fruits 1.2–2.0 mm long, with circumscissile dehiscence, the
surface finely wrinkled above the midpoint when dry. Seeds 0.8–1.2 mm in
diameter, rounded along the rim, the surface reddish brown to more commonly
black. 2n=32. July–October.
Scattered nearly
throughout the state (nearly throughout North America, Central America, South
America; introduced in Europe, Asia, Africa, Australia). Banks of streams and
rivers, bottomland forests, margins of sloughs, and bases of bluffs; also
fallow fields, crop fields, gardens, pastures, levees, farmyards, roadsides,
railroads, and open, disturbed areas.