Acorus americanus
Acoraceae
American sweet-flag, belle-angélique, several-vein sweetflag, sweet-flag
sweet-flag family
horizontal, creeping at or near surface, branched.
repent, branched rhizomes.
absent.
basally white with pink or red, otherwise bright green;
major veins 2–6, ± equally raised above leaf surface;
cross section swollen in center, gradually tapering to ends.
not differentiated into petiole and blade, equitant, sword-shaped, larger than 1.5 cm;
venation parallel along length of leaf.
spadices, from 3-angled axis (peduncle fused with proximal portion of sympodial leaf, i.e., leaf encircling terminal inflorescence), distal sympodial leaf extending beyond spadix;
true spathe absent;
spadix nearly cylindric, tapering, apex obtuse.
2–3 mm;
pollen grains usually deeply staining in aniline blue.
bisexual;
tepals 6;
stamens 6, distinct;
ovariesy 1, (1–)3-locular, sessile;
stigmas sessile (styles essentially absent), minute.
obpyramidal, 4–6 mm.
berries;
pericarp thin, leathery.
(1–)6(–14), tan, narrowly oblong to obovate, (2–)3–4 mm.
1–6(–14), from apex of locule.
leaves to 1.45 m; sheathing base (proximal part of leaf) 18.1–51.8(–58.8) cm;
distal part of leaf 31.2–88.6(–100.4) × 0.3–1.2 cm, usually slightly longer to more than 2 times length of distal leaf, margins usually entire.
leaf (46–)56.8–148(–166.7) cm, usually equal to or slightly longer than vegetative leaves; sheathing base (20.9–)25.3–74.1(–100.2) cm;
distal part of leaf (20.9–)27.9–77.9(–92.6) × 0.3–1.3 cm.
3.3–7.4(–8.7) cm × 4.7–10(–13.3) mm at anthesis; fruiting spadix 3.5–7.8(–8.8) cm × 6.9–18.2 mm.
= 24.
Acorus americanus
Acoraceae
Acorus americanus, a fertile diploid, occurs from northeastern United States across Canada and the northern plains. Specimens from central Siberia with similar leaf venation were examined, and the species is perhaps holarctic in distribution. Examination of additional material is necessary to determine if northern Asian diploid plants are conspecific with A. americanus. In North America, Native Americans probably played a significant role in the present-day distribution of A. americanus because sweet-flag rhizomes and plants were valued by many groups and were objects of trade. Disjunct populations occur in localities that are often near old Native American village sites or camping areas (M. R. Gilmore 1931).
Acorus americanus is susceptible to infection by Uromyces sparganii (Uredinales).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Acorus historically was recognized as an aberrant genus within Araceae, but much evidence supports its treatment as a separate family and the removal of this family from Arales (M. H. Grayum 1987). Other than the absence of a close association with Arales, the phylogenetic affinities of Acoraceae remain unclear. Evidence based on DNA sequences fails to show any close relationships between Acorus and other genera, and instead supports Acorus as the oldest extant lineage of monocotyledons (M. R. Duvall et al. 1993).
The removal of Acorus from Araceae is supported by the absence of a spathe and the unique vasculature of the structure traditionally interpreted as a spathe (T. S. Ray 1987). The structure that has been called a spathe in Acorus is not morphologically equivalent to the spathe of Araceae; instead it is interpreted as the distal part of the sympodial leaf. The proximal part of the sympodial leaf is adnate to the peduncle, forming a 3-angled axis that bears the inflorescence.
Genera 1, species 3–6 (2 species in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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