Sagittaria graminea
Sagittaria guayanensis
grass-leaf arrowhead, grassy arrowhead, sagittaire a feuilles de graminees
guyanese 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.
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.
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.
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.
Sagittaria graminea
Sagittaria guayanensis
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.)
The name has often been spelled guyanensis (K. Rataj 1972), which is incorrect. Sagittaria guayanensis was the spelling in the protologue. The holotype was collected by Humboldt and Bonpland in Colombia, not Guyana. The type citation is Colombia: Guainia: in wetlands near the sugar mill of Don Felix Farreras and the city of Bolivar. The type is supposedly at Paris, as with all HBK types; however, we (with the help of Alicia Lourteig) have been unable to locate it. MO has a fragment, however. Rataj did designate a neotype: Suriname, Hostman 870 (TCD!). The fragment at MO takes precedence over this neotype.
Sagittaria guayanensis was divided into two subspecies, S. guayanensis subsp. guayanensis from the Neotropics and subsp. lappula (D. Don) Bogin from the Paleotropics. The two subspecies were separated by the shape and size of the fruit in addition to their distribution. Sagittaria guayanensis subsp. lappula has compressed achenes longer than 2.5 mm, whereas subsp. guayanensis has plump achenes shorter than 2.5 mm (C. Bogin 1955).
Subspecies 2 (1 in the flora).
(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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