26. Carex amphibola Steud.
Pl. 36 e–g; Map 139
Plants mostly without noticeable rhizomes,
forming dense tufts or rarely loose clumps, green to light green or yellowish
green. Flowering stems 15–80 cm long, erect to spreading, brown or dark reddish
purple at the base. Leaf blades 1–50 cm long, 3–7 mm wide, flat. Leaf sheaths
glabrous, the tip truncate or shallowly concave, the lowermost, nearly
bladeless sheaths brown or dark reddish purple. Spikes 3–5 per stem, the bracts
of the uppermost pistillate spikes longer than the inflorescence. Staminate
spike 7–35 mm long, sessile or short-stalked, the stalk smooth. Staminate
scales 3.6–4.9 mm long, narrowly oblong to narrowly ovate, white to light brown
with green midrib, occasionally with sparse, red spots. Pistillate spikes 5–25
mm long, 4.5–9.5 mm wide, the uppermost sessile or short-stalked, the lowermost
short- to more commonly long-stalked, the stalks smooth, ascending, with 3–18
strongly overlapping perigynia, these several-ranked, in a spiral pattern
around the axis. Pistillate scales 2.0–5.3 mm long, the lowermost ones with the
bodies as long as or longer than the associated perigynia, ovate to broadly
ovate, the tip pointed and with a short to long, rough-margined awn, white with
green midrib, sometimes with reddish purple spots or streaks. Perigynia 4.2–5.2
mm long, 1.5–2.2 mm wide, 2.5–3.0 times as long as wide, ascending, narrowly
elliptic to obovate in outline, the tip pointed, without a beak, slightly
tapered to a broad, more or less rounded base, bluntly triangular in
cross-section. Fruits 3.0–3.7 mm long, the main body (excluding beak and
stalklike base) 1.9–2.4 mm long, the beak 0.3–0.6 mm long, straight. 2n=54,
56. April–July.
Scattered nearly throughout Missouri, but uncommon in the Glaciated and Unglaciated Plains Divisions (eastern U.S. west to Illinois and Texas). Bottomland forests and margins of streams and rivers; less
commonly in mesic upland forests and upland prairies.
Steyermark (1963) treated the C.
amphibola complex as a single species with four varieties and discussed
taxonomic problems within the group that had led some botanists to recognize a
greater number of species for the region. Naczi (1992, 1993) has studied the
group intensively and described several new species as segregates from C.
amphibola. Thus, the complex is treated here as consisting of four closely
related species, C. amphibola in the strict sense, C. corrugata, C.
grisea, and C. planispicata. Readers are advised, however, that
these species are defined differently than were the four varieties accepted by
Steyermark (1963), and there is not a one-to-one correspondence between them.
For further discussion, see the treatments of C. corrugata and C.
grisea.