ALISMATACEAE – WATER PLANTAIN FAMILY
Plant: herbs (annual or mostly perennial) – mostly aquatic; streams, swamps, and muddy ground Stem: leaves form a sheath for the stem Root: mostly fibrous, sometimes forming tubers Leaves: simple, basal, smooth, arrow-shaped and oval or lance-shaped, veins often prominent, only main veins parallel Flowers: perfect or imperfect (monoecious; Sagittaria); flowers whorled or opposite, 3 green, separate and persistent sepals; 3 petals, usually white or pinkish; stamens usually 3-6 to numerous and spiraled; 3 to many pistils in a ring or a cluster, ovary superior, 1 ovule, carpels 6 to numerous Fruit: usually a dry seed (achene or follicle) Other: most common in temperate areas; Monocotyledons Group Genera: 11+ genera; locally Alisma (water-plantains), Sagittaria (arrow- heads), and Echinodorus (bur-heads)
WARNING – family descriptions are only a layman’s guide and should not be used as definitive Alismataceae (Water-Plantain Family) – corolla with 3 petals (usually white but sometimes pinkish); calyx of 3 separate sepals; leaves simple, basal, and only the main veins are parallel; fruit an achene or follicle
Examples of Common Genera
Pistils in clustered heads, achene fruits ring of single pistils, flattened, three bracts, Northern [Large-Flowered] flat receptacle no bracteoles Broadleaf [Common] Arrowhead Water Plantain (secondary, usually Sagittaria latifolia Willd. Alisma triviale Pursh smaller outer bracts), perfect or imperfect (monoecious)
Pistils in clustered heads, achene fruits flattened, three bracts plus several bracteoles, perfect
Creeping Burhead Echinodorus cordifolius (L.) Griseb. ALISMATACEAE – WATER PLANTAIN FAMILY
American [Southern] Water Plantain; Alisma subcordatum Raf. Northern [Large-Flowered] Water Plantain; Alisma triviale Pursh Creeping Burhead; Echinodorus cordifolius (L.) Griseb. Midwestern [Shortbeak] Arrowhead; Sagittaria brevirostra Mack. & Bush Hooded [Mississippi] Arrowhead; Sagittaria calycina Engelm. var. calycina Grassy [Grass-Leaved] Arrowhead; Sagittaria graminea Michx. Broadleaf [Common] Arrowhead; Sagittaria latifolia Willd. Delta Arrowhead; Sagittaria platyphylla (Engelm.) J.G. Sm. American [Southern] Water Plantain USDA Alisma subcordatum Raf. Alismataceae (Water-Plantain Family) River Road Park, Clearwater Lake, Wayne County, Missouri Notes: 3-petaled flower, white, petals 1 - 2.5 mm, sepals about as long as petals, numerous flowering stalks on long stem; leaves ovate and basal with long slender petiole, acute tip, less than 2- 3x as long as broad; fruit ring usually less than 3.5 - 4 mm; muddy shores; summer to early fall [V Max Brown, 2011] Northern [Large-Flowered] USDA Water Plantain Alisma triviale Pursh Alismataceae (Water-Plantain Family) Maumee Bay State Park, Lucas County, Ohio Notes: 3-petaled flower, white, petals 3+ mm, sepals usually half to two-thirds length of petals, numerous flowering stalks on long stem; leaves ovate and basal with long slender petiole, acute tip, less than 2x as long as broad; fruit ring 3.5 to 5 mm, muddy shores; summer to early fall [V Max Brown, 2006] Creeping Burhead USDA Echinodorus cordifolius (L.) Griseb. Alismataceae (Water-Plantain Family) Mingo National Wildlife Refuge, Stoddard County, Missouri Notes: 3-petaled perfect flower, white, many stamens, flowers on long pedicels, mostly in whorls of 3 to 10+ flowers, at maturity inflorescence is prostrate and often rooting at nodes; leaves vary but mostly ovate with cordate base; fruit with 8 ribs; muddy shores or aquatic; July to October [V Max Brown, 2011] Midwestern [Shortbeak] USDA Arrowhead Sagittaria brevirostra Mack. & Bush Alismataceae (Water-Plantain Family) Otter Slough State Wildlife Management Area, Stoddard County, Missouri Notes: 3-petaled flower, white, many stamens, bracts free or more often fused in basal portion, linear to lanceolate, acute at tip, and often up to 4+ cm; lower whorls pistillate with reflexed sepals; leaves vary, emergent leaves usually sagittate to hastate; fruit obovate (up to 1.5 mm) with beak ascending; muddy shores and margins of bodies of water; early summer to early fall [V Max Brown, 2017] Hooded [Mississippi] USDA Arrowhead Sagittaria calycina Engelm. var. calycina Alismataceae (Water-Plantain Family) Wire Road Conservation Area, Stone County, Missouri Notes: 3-petaled perfect flower, white, many stamens, sepals fused in basal portion and ascending to appressed in the fruiting stage, flowers on long pedicels, 1 to 8 whorls of flowers at maturity; leaves vary, emergent leaves usually sagittate to hastate; fruit obovate with a beak (up to 2 mm in length); muddy shores and margins of bodies of water; early summer to early fall [V Max Brown, 2014] Grassy [Grass-Leaved] Arrowhead USDA Sagittaria graminea Michx. Alismataceae (Water-Plantain Family) Ottawa National Wildlife Refuge, Ottawa County, Ohio Notes: 3-petaled flower (monoecious), upper staminate flowers white (or pinkish), on long pedicels, mostly in whorls of 3, sepals ovate, rounded and fused at base, lower pistillate flowers similar; leaves linear to lance- linear with blades 4x longer than wide; muddy shores or aquatic; summer to early fall [V Max Brown, 2008] Broadleaf [Common] Arrowhead USDA [Duck Potato] Sagittaria latifolia Willd. Alismataceae (Water-Plantain Family) Maumee River Metroparks, Lucas County, Ohio Notes: 3-petaled flower, white, often falling early, 20+ stamens, all flowers on long pedicels, mostly in whorls of 3, lower flowers pistillate; leaves vary from narrow to broad, arrowhead-shaped (hastate to sagittate); most common species; muddy shores or aquatic; summer to fall [V Max Brown, 2005] Delta Arrowhead USDA Sagittaria platyphylla (Engelm.) J.G. Sm. Alismataceae (Water-Plantain Family) Near Heber Springs, Cleburne County, Arkansas Notes: perennial, monoecious; 3-petaled flower, upper staminate flowers white (or pinkish), on long pedicels, mostly in whorls of 3, sepals ovate and reflexed in fruit, rounded and fused at base, lower pistillate flowers similar, node bracts with fused base and triangular tips; leaves lanceolate to somewhat ovate, up to 45+ cm, usually without loves but sometimes with a pair of basal lobes; muddy shores or aquatic; fruit an achene to 2+ mm with usually (not always) a curved beak from 0.3 to 0.7mm; late spring to summer to early fall [V Max Brown, 2017]
Beak here about 0.7 mm