Amaranthaceae - Amaranth Family
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AMARANTHACEAE - AMARANTH FAMILY Plant: mostly herbs (annual or perennial) - some termed weeds such as the pigweeds; rarely shrubs, vines or trees Stem: Root: sometimes with tap root Leaves: mostly simple, mostly entire, alternate or opposite, may be curved, wavy, crinkled, or waxy; spines ± at base of leaves; no stipules Flowers: mostly perfect but sometimes imperfect (monoecious or dioecious); no petals; mostly 2-5 (rarely 0 or 1) sepals, greenish to purplish, inconspicuous in dense terminal clusters or spikes; bracts greenish and tough; stamens usually 5 or rarely less, usually matching sepals; ovary superior and 1 chambered, 1 pistil, carpels usually 2 or (3-5), 1-2+ styles or absent Fruit: 1-seeded utricle or nutlet, sometimes a capsule, berry or drupe Other: most abundant in tropics, locally introduced and especially common at borders of farm fields; Dicotyledons Group Genera: 69+ genera; locally Achyranthes, Alternanthera, Amaranthus (amaranth), Celosia, Froelichia (cottonweed), Iresine (bloodleaf) WARNING – family descriptions are only a layman’s guide and should not be used as definitive Flower Morphology in the The Amaranthus genus is complex and Amaranthaceae (Amaranth Family) difficult to ID Examples of common genera Spiny Amaranth Amaranthus spinosus L. (Introduced) Plains [Field] Snakecotton [Cottonweed] Froelichia floridana (Nutt.) Moq. Silverhead [Saltweed] Blutaparon vermiculare (L.) Mears Juda's Bush [Eastern Bloodleaf] Iresine rhizomatosa Standl. AMARANTHACEAE - AMARANTH FAMILY Alligator Weed; Alternanthera philoxeroides (Mart.) Griseb. (Introduced) Powell's Amaranth; Amaranthus powellii S. Watson ssp. powellii Rough [Redroot] Pigweed [Rough Green Amaranth]; Amaranthus retroflexus L. Spiny Amaranth; Amaranthus spinosus L. Silverhead [Saltweed]; Blutaparon vermiculare (L.) Mears Plains [Field] Snakecotton [Cottonweed]; Froelichia floridana (Nutt.) Moq. Slender Snakecotton [Cottonweed]; Froelichia gracilis (Hook.) Moq. Juda's Bush [Eastern Bloodleaf]; Iresine rhizomatosa Standl. *some species have 2 pages to better illustrate flower structure Alligator Weed USDA Alternanthera philoxeroides (Mart.) Griseb. (Introduced) Amaranthaceae (Amaranth Family) Destin Area, Okaloosa County, Florida Notes: inflorescence of white papery flowers on long peduncles, 5 sepals; leaves opposite, somewhat blunt tips, glabrous, elliptical to lanceolate; stem hollow (floating) with roots at nodes, sprawling; aquatic (floating, often in mats), also on shorelines; winter to fall? [V Max Brown, 2017] Powell's Amaranth – P 1 USDA Amaranthus powellii S. Watson ssp. powellii Amaranthaceae (Amaranth Family) Near Strafford, Greene County, Missouri Notes: monoecious; staminate and pistillate flowers with 3 to 5 sepals (no petals), greenish, terminal panicle of spikes and axillary spikes, spikes usually larger in diameter than a pencil (see page 2 for flower structure details); leaves elliptical-ovate-lanceolate, tapered at base, bluntly pointed tip, petioles very long, under surface hairy particularly on veins; stem and leaf stalk finely hairy, no nodal spines; common plant, especially at edges of cultivated fields; summer to fall [V Max Brown, 2017] Powell's Amaranth – P 2 Flowers below are Amaranthus powellii S. Watson ssp. Powellii [V Max Brown, 2017] somewhat immature Staminate Flower Pistillate Flowers Stamens Sepal Stem (main axis) densely pubescent – flower clusters sessile to stem – outer bracts longer Pistillate flowers – 3-5 sepals, 2-4 mm long Staminate flower – 3-5 sepals, 2.0 to than sepals (above 2 mm, immature), lanceolate, tapered 2.5+ mm long, lanceolate to to a point usually with midrib extending into somewhat ovate, sharp pointed tip an awn – 3 stigmas with an awn from midrib extension – 3 to 5 stamens Bract Flower Immature Seed Fruit (upper part with immature seed) – note circumscissile Outer bracts 4 to 7 mm (here 3 mm, dehiscence of fruit – seed 1.0 to 1.2+ mm in diameter (here immature), lanceolate, green midrib about 1.2 mm) – black to dark reddish brown at maturity extending into an awn Rough [Redroot] Pigweed USDA [Rough Green Amaranth] – P 1 Amaranthus retroflexus L. Amaranthaceae (Amaranth Family) Near Strafford, Greene County, Missouri Notes: monoecious; 5 (4) sepaled flower (no petals), greenish, terminal panicle composed of branching spikes, lateral spikes from axils, spikes thick (like thumb) (see page 2 for flower structure details); leaves ovate-lanceolate, petioles long; stem and leaf stalk hairy, no nodal spines; roots often red; common plant, especially at edges of cultivated fields (many common names); summer to fall [V Max Brown, 2017] Rough [Redroot] Pigweed [Rough Green Amaranth] – P 2 Amaranthus retroflexus L. [V Max Brown, 2017] Staminate Flower Pistillate Flowers Stamens Staminate flower – sepals 5, rarely 4, 2 to 2.5+ mm long, sharp pointed tip with an awn from midrib extension, usually somewhat reflexed – mostly 5 stamens Sepals Stem (main axis) densely pubescent – flower clusters sessile to stem – outer bracts longer than sepals Bract Flower Seed Pistillate flowers – usually 5, rarely 4 sepals, 2- 3 mm long, usually somewhat reflexed, tips rounded, sometimes notched, may or may not have a short awn extension from the green Fruit (upper part with seed) – 3 stigmas - note midrib circumscissile dehiscence of fruit – seed 0.9 Outer bracts 4 to 8 mm, lanceolate, to 1.2 mm in diameter (here about 1.0 mm) – green midrib extending into an awn black to dark reddish brown Spiny Amaranth – P1 USDA Amaranthus spinosus L. (Introduced) Amaranthaceae (Amaranth Family) Near Strafford, Greene County, Missouri Notes: monoecious; no petals, bracts shorter than sepals, 5 green sepals, flowers in clusters - both terminal (usually staminate) and in axils or nodes (usually pistillate) (see detail photos on page 2); leaves lanceolate to elliptical, widest below middle, long petiolate; stems often branching, usually a pair of spines at axils or nodes; tall plant often in disturbed areas; summer to fall [V Max Brown, 2017] Paired nodal spines Spiny Amaranth – P2 Amaranthus spinosus L. (Introduced) [V Max Brown, 2017] Bracts to 1.0 mm, tapered to sharp point, green midrib extending into sharp point (shorter than sepals); 5 sepals on both staminate and pistillate flowers to about 1.6 mm, tapered to sharp point; 5 stamens and 3 stigmas Silverhead [Saltweed] USDA Blutaparon vermiculare (L.) Mears Amaranthaceae (Amaranth Family) Cedar Key, Levy county, Florida Notes: vine; dioecious; inflorescences white to pink (drying silver-white), cylindrical, composed of tepals; leaves opposite, fleshy, linear to somewhat lanceolate; stem mostly prostrate, fleshy, glabrous and branching; a costal, salt tolerant plant; year round flowering [V Max Brown, 2012] Plains [Field] Snakecotton USDA [Cottonweed] Froelichia floridana (Nutt.) Moq. Amaranthaceae (Amaranth Family) Alley Springs, Ozark National Riverways, Shannon County, Missouri Notes: no petals, 5-lobed flask-shaped calyx, small opening at top, calyx tube with deeply toothed longitudinal wings on the sides (see photo on right); leaves lanceolate, largest leaves up to 3 cm wide; stems often branching from base, up to 2 m; cottony (hairy) plant; summer to early fall [V Max Brown, 2010] Slender Snakecotton [Cottonweed] USDA Froelichia gracilis (Hook.) Moq. Amaranthaceae (Amaranth Family) Wire Road Conservation Area, Stone County, Missouri Notes: no petals, calyx conical shaped, small opening at top, sessile, rows of sharp spines; leaves lanceolate, largest leaves up to 15 mm wide, 12 cm long, mostly lanceolate; stems often branching from base, up to 70+ cm; cottony (hairy) plant; late spring to early fall [V Max Brown, 2014] Juda's Bush [Eastern Bloodleaf] USDA Iresine rhizomatosa Standl. Amaranthaceae (Amaranth Family) Busiek State Forest and Wildlife Area, Christian County, Missouri Notes: dioecious; inflorescences terminal and in upper axils, flowers small and white; leaves opposite, petiolate, mostly ovate, thin, entire or finely toothed; bottomlands and stream banks; late summer to fall [V Max Brown, 2010].