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delta arrowhead

acid-water arrowhead, Engelmann's arrowhead

Habit Herbs, perennial, to 150 cm; rhizomes absent; stolons present; corms present. Herbs, perennial, to 70 cm; rhizomes absent; stolons present; corms present.
Leaves

submersed and emersed; submersed sessile, phyllodial, flattened, to 26 × 0.5 cm; emersed with petiole ± triangular, 21–70.5 cm, blade linear-ovate to ovate, 4.6–16.4 × 0.7–6.1 cm.

emersed;

petiole triangular, 10–40 cm;

blade sagittate, 4.5–10 × 0.2–2 cm, basal lobes ± equal to remainder of blade.

Inflorescences

racemes, of 3–9 whorls, emersed, 2.5–10 × 2–4.5 cm;

peduncles 22–60 cm;

bracts connate more than ¼ total length, lanceolate, 3–5.5 mm, delicate, not papillose; fruiting pedicels spreading to recurved, cylindric, 0.5–3 cm.

racemes, of 2–4 whorls, emersed, 5–14 × 2–4 cm;

peduncles 20–38 cm;

bracts distinct or if connate, then less than ¼ total length, lanceolate, 5–25 mm, not papillose; fruiting pedicels spreading, cylindric, 1.5–3.5 cm.

Flowers

to 1.8 cm diam.;

sepals spreading to recurved, not enclosing flower or fruiting head;

filaments dilated, longer than anthers, pubescent; pistillate pedicellate, without ring of sterile stamens.

to 30 mm diam.;

sepals recurved to spreading, not enclosing flower or fruiting head;

filaments linear, longer than to equal length of anther, glabrous; pistillate pedicellate, without ring of sterile stamens.

Fruiting

heads 0.7–1.2 cm diam.;

achenes oblanceoloid, not abaxially keeled, 1.2–2 × 0.8–1.2 mm, beaked;

faces tuberculate, wings absent, glands absent;

beak lateral, horizontal to erect, 0.3–0.6 mm.

heads 1–1.8 cm diam.;

achenes cuneate to obovoid, without abaxial keel, 2.4–4 × 1.5–3.8 mm, beaked;

faces not tuberculate, wings 1–3, ± entire, glands 1–2;

beak lateral, obliquely ascending, (0.7–)1–2.1 mm.

2n

= 22.

= 22.

Sagittaria platyphylla

Sagittaria engelmanniana

Phenology Flowering summer–fall. Flowering late spring–summer (Jun–Sep).
Habitat Streams and lakes Acid waters of ponds, lakes, bogs, and streams
Elevation 0–900 m (0–3000 ft) 0–1100 m (0–3600 ft)
Distribution
from FNA
AL; AR; FL; GA; IL; KY; LA; MO; MS; OH; OK; PA; TN; TX; WV; Mexico (Nuevo León Mexico, sw Mexico); Central America (Panama)
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; CT; DE; FL; GA; MA; MD; MS; NC; NJ; NY; PA; RI; SC; VA; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Sagittaria platyphylla has been accepted at the variety level, i.e., Sagittaria graminea var. platyphylla (C. Bogin 1955; J. W. Wooten 1973; E. O. Beal et al. 1982). After studying dozens of populations in the field from much of its range and hundreds of herbarium specimens, we have concluded that this taxon should be recognized at the specific level instead, a conclusion supported by cladistic analyses of morphologic characters (R. M. Kortright 1998)

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 22. FNA vol. 22.
Parent taxa Alismataceae > Sagittaria Alismataceae > Sagittaria
Sibling taxa
S. ambigua, S. australis, S. brevirostra, S. cristata, S. cuneata, S. demersa, S. engelmanniana, S. fasciculata, S. filiformis, S. graminea, S. guayanensis, S. isoetiformis, S. kurziana, S. lancifolia, S. latifolia, S. longiloba, S. montevidensis, S. papillosa, S. rigida, S. sanfordii, S. secundifolia, S. subulata, S. teres
S. ambigua, S. australis, S. brevirostra, S. cristata, S. cuneata, S. demersa, S. fasciculata, S. filiformis, S. graminea, S. guayanensis, S. isoetiformis, S. kurziana, S. lancifolia, S. latifolia, S. longiloba, S. montevidensis, S. papillosa, S. platyphylla, S. rigida, S. sanfordii, S. secundifolia, S. subulata, S. teres
Synonyms S. graminea var. platyphylla, S.. mohrii
Name authority (Engelmann) J. G. Smith: N. Amer. Sagittaria. 29. (1894) J. G. Smith: Memoirs of the Torrey Botanical Club 5: 25. (1894)
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