Sagittaria graminea
Sagittaria isoetiformis
grass-leaf arrowhead, grassy arrowhead, sagittaire a feuilles de graminees
quillwort arrowhead
submersed or emersed; submersed leaves phyllodial, angled abaxially, flattened adaxially, 6.4–35 × 0.5–4 cm; emersed with petiole triangular, 6.5–17 cm, blade linear to linear-oblanceolate, 2.5–17.4 × 0.2–4 cm.
emersed or submersed, phyllodial or rarely dilated apically, flattened, 4–40 cm × 0.05–0.4(–0.5) cm.
racemes or panicles, of 1–12 whorls, emersed, 2.5–21 × 1–8 cm;
peduncles 6.5–29.7 cm;
bracts connate more than to equal to ¼ total length, broadly subulate to lanceolate, 20–50 mm, coarse, not papillose; fruiting pedicels spreading, cylindric, 0.5–5 cm.
racemes, of 1–5 whorls, emersed, 2–20 × 1.5–12 cm;
peduncles 7–59 cm;
bracts connate more than or equal to ¼ total length, oblanceolate, 0.2–0.3 mm, delicate, not papillose; fruiting pedicels spreading, cylindric, 0.5–6 cm.
to 2.3 cm diam.;
sepals recurved to spreading, not enclosing flower;
filaments dilated, shorter than anthers, pubescent;
pistillate flowers pedicellate, without ring of sterile stamens.
to 1.3 cm diam.;
sepals recurved to spreading, not enclosing flower;
filaments dilated, shorter than anthers, minutely tomentose;
pistillate pedicellate, without ring of sterile stamens.
heads 0.6–1.5 cm diam.;
achenes oblanceoloid, without abaxial keel, 1.5–2.8 × 1.1–1.5 mm, beaked;
faces not tuberculate, abaxial wings 0–1, ± entire, glands 1–2;
beak lateral, erect, 0.2 mm.
heads 0.5–1 cm diam.;
achenes obovoid, abaxially keeled, 2.2–2.8 × 1.5–2 mm, beaked;
faces not tuberculate, wings 1–2, ± entire, glands 3–5;
beak lateral, incurved-erect, 0.2 mm.
Sagittaria graminea
Sagittaria isoetiformis
Seven varieties of Sagittaria graminea have been recognized, i.e., var. graminea, var. platyphylla Engelmann, var. teres (S. Watson) Bogin, var. weatherbiana Fernald, var. cristata (Engelmann) Bogin, var. chapmanii J. G. Smith, and var. macrocarpa (J. G. Smith) Bogin (C. Bogin 1955). We accept only one infraspecific rank, i.e., subspecies. Consequently, we have made the appropriate combinations. We accept all of the taxa accepted by Bogin at the varietal level. At specific level we accept Bogin’s var. platyphylla, var. teres, and var. cristata and at subspecific level his var. graminea, var. chapmanii, and var. weatherbiana.
Sagittaria graminea var. macrocarpa actually is synonymous with var. graminea (E. O. Beal 1960b). We therefore are following Beal in recognizing var. macrocarpa sensu Bogin as S. fasciculata. We also accept var. platyphylla, var. teres, and var. cristata at the specific level, leaving only three subspecies. These subspecies can be separated by the branching of the inflorescence and the length of pistillate pedicels.
Subspecies 3 (3 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Sagittaria isoetiformis has often been misidentified as Sagittaria teres (E. O. Beal 1960b). The two species can be separated, however: S. teres has nearly terete phyllodia, whereas S. isoetiformis has flattened phyllodia (R. K. Godfrey and P. Adams 1964). A study of the genetics of the two species shows them to be genetically different, and the data indicate the two taxa actually should be considered at the specific level. The two species are capable of CAM photosynthesis, a process very uncommon in the genus and found among none of their supposedly closely related species (A. L. Edwards, pers. comm.).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Inflorescences panicles. | subsp. chapmanii |
1. Inflorescences racemes. | → 2 |
2. Pistillate pedicels 0.5–3 cm; phyllodia less than 1 cm wide | subsp. graminea |
2. Pistillate pedicels 2.1–5 cm; phyllodia more than 1 cm wide | subsp. weatherbiana |
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