FNA: Carex muehlenbergii var. enervis vs. Carex sect. Phaestoglochin

Phenology

Fruiting late spring–early summer.

Habitat

Dry grasslands, open forests, commonly on sand

Elevation

10–300 m (0–1000 ft)

Distribution

AL; AR; CT; GA; IA; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WV; ON

[BONAP county map]

Mainly in the temperate regions of the Northern Hemisphere

Discussion

The distribution and ecology of Carex muehlenbergii var. enervis are unclear due to confusion with var. muehlenbergii. Plants of var. muehlenbergii that have a veinless perigynium have often been misidentified as var. enervis, but those plants are otherwise identical to var. muehlenbergii. Carex muehlenbergii var. muehlenbergii usually occurs on basic to slightly acidic soils; var. enervis often occurs on more acidic soils. It is not clear, however, whether that correlation is consistent.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species ca. 27 (25 in the flora).

K. K. Mackenzie (1931–1935, parts 2–3, pp. 41–53) combined sections Phaestoglochin Dumortier and Bracteosae Pax; sect. Bracteosae is now considered to be endemic to Central and South America.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key

1. Proximal leaf sheaths longitudinally green-and-white-striped and with prominent green cross veins, usually loose; widest leaf blade 3–10 mm wide.	→ 2
1. Proximal leaf sheaths not or indistinctly striped, without prominent cross veins, tight; widest leaf blade 0.5–4(–5) mm wide.	→ 5
2. Bodies of pistillate scales 2.2–4.4 × 1.2–2.4 mm, mostly more than 1/2 length of perigynia, apex acuminate to awned; anthers 1.5–3 mm.	→ 3
2. Bodies of pistillate scales 1.5–2.5 × 1.1–1.8 mm, mostly less than 1/2 length of perigynia, apex obtuse to acuminate or shortly awned; anthers 0.7–1.3 mm.	→ 4
3. Fronts of leaf sheaths white, hyaline, thin, and fragile at mouth, backs not white spotted.	C. gravida
3. Fronts of leaf sheaths yellow or brown, thick, and firm at mouth, backs often white spotted.	C. aggregata
4. Proximal internodes of inflorescences usually not more than 1 cm, usually less than 2 times as long as proximal spikes; bodies of perigynia with narrow wing not more than 0.1 mm wide.	C. cephaloidea
4. Proximal internodes of inflorescences usually 2+ cm, at least 2 times as long as proximal spikes; bodies of perigynia with narrow wing 0.1–0.2 mm wide, at least distally.	C. sparganioides
5. Perigynium beak margins smooth.	→ 6
5. Perigynium beak margins serrulate.	→ 9
6. Pistillate scales not more than 1/3–3/4 length of perigynia; bases of perigynia not longitudinally striate on adaxial face.	C. leavenworthii
6. Pistillate scales at least 3/4 length of perigynia; bases of perigynia longitudinally striate on adaxial side.	→ 7
7. Perigynia ascending, 1.8–2.3 mm wide; pistillate scales 1.8–2.2 mm wide; achenes 1.6–2.7 mm.	C. vallicola
7. Perigynia spreading to reflexed when mature, 1–1.8 mm wide; pistillate scales 0.8–1.6 mm wide; achenes 1.3–1.6 mm.	→ 8
8. Perigynia (1.2–)1.4–1.8 mm wide, 1.5–2.3 times as long as wide; widest leaf blades 1.4–3 mm wide.	C. retroflexa
8. Perigynia 1–1.3 mm wide, 2.3–3.1 times as long as wide; widest leaf blades 1–1.7 mm wide.	C. texensis
9. Proximal bracts at least 2 times as long as inflorescences, 6 cm or longer; perigynia 1.9–3 mm wide.	→ 10
9. Proximal bracts shorter than to less than 2 times as long as inflorescences, to 6(–11) cm; if longer, perigynia 0.7–1.8 mm wide.	→ 11
10. Proximal nodes of inflorescences as long as or longer than proximal spikes; perigynium beak 0.8–1.2 mm.	C. arkansana
10. Proximal nodes of inflorescences shorter than proximal spikes; perigynium beak (1–)1.4–1.8 mm.	C. perdentata
11. Inflorescences lax; proximal internodes more than 2 times as long as proximal spikes.	→ 12
11. Inflorescences dense; proximal internodes less than 2 times as long as proximal spikes.	→ 17
12. Pistillate scales (2.5–)2.7–4.5 mm; perigynia not or only slightly spongy thickened at base, not longitudinally striate.	→ 13
12. Pistillate scales 1–2.5 mm; perigynia spongy thickened at base and longitudinally striate adaxially.	→ 14
13. Pistillate scales hyaline or pale brown, shorter than perigynia; perigynia 1.7–2.6 mm wide.	C. divulsa
13. Pistillate scales brown, exceeding perigynia; perigynia 1.2–1.5 mm wide.	C. hookeriana
14. Stigmas straight, twisted or slightly coiled, 0.03–0.06 mm wide; spongy bases of perigynia 1–1.5 mm, 0.2–0.3 times length of perigynia.	→ 15
14. Stigmas usually tightly coiled, 0.05–0.1 mm wide; spongy bases of perigynia 0.5–1.3 mm, not more than 0.2 times length of perigynia.	→ 16
15. Perigynia 1.5–3 times as long as wide; achenes 1–1.4 mm wide, not more than 2 times as long as wide.	C. radiata
15. Perigynia 3–5 times as long as wide; achenes 0.8–1 mm wide, 2– 2.4 times as long as wide.	C. socialis
16. Widest leaf blades 1.8–2.6 mm wide; base of culms 1.5–2.2 mm wide.	C. rosea
16. Widest leaf blades 0.9–1.5 mm at widest; base of culms 0.7–1.4 mm wide.	C. appalachica
17. Bodies of pistillate scales at least as long as and wide as perigynia, largely obscuring them.	→ 18
17. Bodies of pistillate scales shorter than perigynia and narrower; perigynia easily visible.	→ 22
18. Pistillate scales with awn to 1–4 mm.	→ 19
18. Pistillate scales acute or with awn to 1 mm.	→ 20
19. Perigynia 2.2–3 mm wide, distinctly veined abaxially; achenes 1.9–2.5 × 1.5–2 mm.	C. austrina
19. Perigynia 1.2–1.5 mm wide, veinless or obscurely veined abaxially; achenes 1.5–1.7 × 1.1–1.2 mm.	C. hookeriana
20. Inflorescences globose or ovoid heads, 0.8–2 cm × 6–15 mm; proximal spikes not distinct.	C. hoodii
20. Inflorescences oblong, 1.5–5 cm × 6–10 mm; proximal spikes ± distinct.	→ 21
21. Perigynia ascending to spreading; beak 0.6–1.3 mm; pistillate scales 3.4–4 × 1.6–2 mm; proximal bracts usually shorter than spikes.	C. occidentalis
21. Perigynia erect; beak 1.2–3 mm; pistillate scales 4–5.2 × 2–2.8 mm; proximal bracts longer than spikes, often longer than inflorescences.	C. tumulicola
22. Bodies of pistillate scales not more than 2/3 length of perigynia; inflorescences dense, spikes individually indistinct.	→ 23
22. Bodies of pistillate scales at least 2/3 length of perigynia; inflorescences dense or lax.	→ 24
23. Perigynium bodies elliptic to circular, widest point at 0.4–0.55 of length of body; beak 0.7–1.1 mm, apical teeth 0.3–0.5 mm.	C. cephalophora
23. Perigynium bodies ovate, widest point at 0.25–0.4 of length of body; beak 0.3– 0.8 mm, apical teeth 0.1–0.3 mm.	C. leavenworthii
24. Perigynium beak obscurely toothed at apex, apical teeth not more than 0.2 mm; widest leaf blades 2 mm wide.	C. vallicola
24. Perigynium beak distinctly toothed at apex, apical teeth mostly 0.2–0.7+ mm; widest leaf blades 2 mm wide.	→ 25
25. Ligules 4–8 mm, distinctly longer than wide; basal scales and sheaths frequently tinged red or purple.	C. spicata
25. Ligules not more than 4(–5) mm, as wide as or wider than long; basal scales and sheaths brown or black, without trace of red or purple.	→ 26
26. Pistillate scales, except for midvein, dark brown.	C. muricata
26. Pistillate scales, except for midvein, hyaline or brown brown.	→ 27
27. Inflorescences dense, globose to ovoid heads, 1–1.5 times as long as wide, spikes not distinct.	C. mesochorea
27. Inflorescences somewhat lax, oblong, (1.5–)2+ times as long as wide, proximal spikes ± distinct.	→ 28
28. Perigynium beak (1–)1.4–1.8 mm, apical teeth (0.5–)1.4–1.8 mm.	C. perdentata
28. Perigynium beak 0.2–1.5 mm, apical teeth 0.2–0.6 mm.	→ 29
29. Perigynia yellow-green, becoming dark brown and glossy when mature, veinless or weakly 7(–11)-veined abaxially.	C. muricata
29. Perigynia yellow or yellow-brown when mature, strongly 9–15-veined abaxially.	→ 30
30. Pistillate scales narrower than perigynia, not more than 2 mm wide, apex acute or with awn to 1.5(–2) mm.	C. muehlenbergii
30. Pistillate scales as wide as perigynia, widest 2+ mm wide, apex with awn to 1.5–4 mm.	C. austrina