Rhynchospora macrostachya
Rhynchospora chalarocephala
tall beaksedge, tall horned beaksedge
loosehead beaksedge
stiffly erect, leafy, triangular, multiribbed.
erect to ascending-arching, slender, nearly terete, multiribbed.
ascending, overtopped by inflorescence;
blades flat proximally, 3–10(–15) mm wide, apex attenuate, trigonous.
terminal and axillary, narrow, clusters of corymbs, clusters dense, mostly broadly turbinate, 13–15 mm;
bracteal leaves mostly exceeding subtended compounds.
spikelet clusters 3–7, widely spaced, clusters loosely turbinate to hemispheric, to 1.3 cm wide.
brown, lanceoloid, 13–15 mm, apex acuminate;
fertile scales lanceolate, 10–13 mm, apex acuminate, midrib shortexcurrent.
brown to pale red-brown, lance-fusiform, 3–5.5 mm;
fertile scales elliptic, 2.5–4 mm, acute, midrib short-excurrent.
longer perianth bristles usually fully 2 times length of fruit body, antrorsely barbellate.
perianth bristles 6, ± equaling tubercle.
1–2 per spikelet, 20–25 mm;
body pyriformobovoid, compressed, 5–6 × 2.6–3.6 mm;
tubercle attenuate, 2-grooved, (15–)18–20(–21) mm.
1 per spikelet, (2.5–)2.7–3.3(–3.5) mm, body pale brown with yellowish center, ± broadly oblong-obovoid distal to stipe, lenticular, 1.5–2 × 0.8–1 mm;
tubercle narrowly triangularsubulate, (1–)1.2–1.5(–2) mm, less than 0.5 mm wide at base.
leaves exceeded by culm;
blades flat, linear, 1–2 mm wide, apex tapering, trigonous.
= 18.
Rhynchospora macrostachya
Rhynchospora chalarocephala
Rhynchospora macrostachya is quickly distinguished from other species of its complex by more compact clusters, arranged on successive mid and distal nodes to present a narrow inflorescence outline. Its perianth bristles and fruit tubercles are the longest in the complex, probably in the entire genus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Some specimens of Rhynchospora chalarocephala are very difficult to distinguish from R. microcephala, and unquestionably intergrades occur in peninsular Florida and the Gulf southern coastal plain. Rhynchospora chalarocephala tends to have longer, paler, narrower spikelets in looser clusters; the dilated part of the fruit body has a narrower, more oblong outline; and the tubercle is both narrower with a narrower base and longer (mostly 1–1.5 mm versus 0.9–1.2 mm in R. micro-cephala). Most material is easily sorted because R. chalarocephala has paler spikelets in turbinate to hemispheric clusters; the dark brown spikelets of R. microcephala are in globose heads.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Go Botany
KS Wildflowers
LA Plants
MD Biodiversity
MI Flora
MO Plants
WildflowerSearch
iNaturalist
USDA Plants Database
