Tropicos | Name - !Eragrostis Wolf

!Eragrostis Wolf

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48. Eragrostis Wolf (love grass)

Plants annual or perennial, with perfect florets or rarely dioecious, sometimes with stolons (short rhizomes often present in E. spectabilis), forming tufts, small clumps, or mats. Flowering stems erect or ascending, sometimes from spreading bases, glabrous or less commonly hairy, sometimes glandular below the nodes. Leaf sheaths glabrous or hairy, especially at the tip, the ligule a line or band of usually short hairs. Leaf blades flat or with inrolled margins, glabrous, roughened, or hairy. Inflorescences open to dense, broad to narrow panicles (sometimes appearing headlike in E. hypnoides), the branches mostly branched again 1 or more times. Spikelets slightly to strongly flattened laterally, with 2 to many florets, disarticulating variously. Glumes usually somewhat unequal in length, shorter than the adjacent lemmas, lanceolate, sharply pointed at the tip, 1(3)‑nerved, glabrous (usually hairy in E. hypnoides). Lemmas lanceolate to ovate, bluntly to more commonly sharply pointed at the tip, 3‑nerved, awnless, rounded on the back or keeled, glabrous (usually hairy along the nerves in E. hypnoides), including the base. Paleas shorter than to more commonly about as long as the lemmas, the 2 nerves sometimes roughened or hairy. Stamens 2 or 3. Fruits oblong to broadly ovate in outline, reddish brown to brown, in a few species with a longitudinal groove on the side opposite the embryo. Two hundred eighty to 350 species, worldwide.

Eragrostis is a large genus in which species determinations can be difficult. Close attention must be paid to details of spikelet morphology. Perennial species may be recognized by the presence of the remains of the previous year’s growth and the production of short, leafy branches from buds located in the basal leaf sheaths. However, some of the perennial species flower during the first year. Most of the species with flat leaf blades develop inrolled margins under droughty conditions or if plants are not pressed soon after they are collected.

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1	Plants stoloniferous, the main stems creeping and rooting at the nodes	(2)
+	Plants without stolons (short rhizomes sometimes present), the main stems erect to ascending, sometimes from spreading bases, not rooting at the nodes or rarely rooting at the lowermost nodes	(3)

2 (1)	Spikelets with perfect florets; lemmas 1.5–2.0 mm long, glabrous; anthers 0.2–0.4 mm long	10 Eragrostis
+	Plants dioecious, the spikelets all staminate or pistillate; lemmas 2.1–4.0 mm long, usually short-hairy along the nerves; anthers 1.4–2.2 mm long	15 Eragrostis reptans

3 (1)	Small, warty, resinous glands (appearing as irregular bumps or shallow pits) scattered along the margins of the leaf blades and in a ring below the nodes of the stems, usually also along the midnerves of the glumes and lemmas	(4)
+	Leaf blade margins and spikelets without warty glands or irregular bumps (but these sometimes found below the nodes of the stems or inflorescences)	(5)

4 (3)	Lemmas 2.0–2.8 mm long; spikelets 2–4 mm wide	3 Eragrostis cilianensis
+	Lemmas 1.5–2.0 mm long; spikelets 1.5–2.0(–2.4) mm wide	12 Eragrostis minor

5 (3)	Inflorescences relatively dense and narrow, the branches stiffly ascending	(6)
+	Inflorescences relatively open and broad at maturity, the branches loosely ascending to spreading (sometimes narrowly ascending when young)	(8)

6 (5)	Spikelets 2–3 mm long; leaf blades 3–8 mm wide, flat; plants annual	8 Eragrostis glomerata
+	Spikelets 4–20 mm long; leaf blades 1–3(–4) mm wide, the margins inrolled; plants perennial	(7)

7 (6)	Spikelets 1–2 mm wide, with 3–12 florets; anthers 0.9–1.5 mm long; basal leaves noticeably longer than those of the stems, conspicuously arched toward the ground	5 Eragrostis curvula
+	Spikelets 2.5–5.0 mm wide, with 9–28 florets; anthers 0.3–0.6 mm long; basal leaves only slightly longer than those of the stems, straight or slightly curved, but not arched toward the ground	16 Eragrostis secundiflora

8 (5)	Spikelets all or mostly less than 3 mm long; spikelets mostly with 2–4 florets	(9)
+	Spikelets all or mostly more than 3 mm long; spikelets mostly with more than 4 florets	(12)

9 (8)	Lemmas rounded on the back, at least below the tip; plants perennial, with hardened bases	9 Eragrostis
+	Lemmas angled or keeled on the back; plants annual, with soft bases	(10)

10 (9)	Leaf sheaths hairy along the margins and at the tip; inflorescence 1/2–2/3 the size of the entire plant; fruit with a longitudinal groove	2 Eragrostis capillaris
+	Leaf sheaths with a line or tufts of hairs at the tip, otherwise glabrous; inflorescence 1/3–1/2 the size of the entire plant; fruit without a longitudinal groove	(11)

11 (10)	Lower glume 2/3 to about as long as the adjacent lemma; paleas persistent on the rachilla after the lemmas and fruits have disarticulated	7 Eragrostis frankii
+	Lower glume 1/4–1/2 as long as the adjacent lemma; paleas eventually disarticulating with the rest of the spikelet, leaving the naked axis	14 Eragrostis pilosa

12 (8)	Plants annual, with soft bases, forming tufts; pattern of spikelet disarticulation beginning with the glumes, then lemmas and fruits from spikelet base to tip, leaving the persistent axis and paleas (the paleas shed eventually in E. pilosa, leaving the naked axis)	(13)
+	Plants perennial, with hardened bases, forming tufts or small clumps; pattern of spikelet disarticulation various, but the joints of the rachilla and paleas always disarticulating with the lemmas and fruits	(16)

13 (12)	Lower glume 1/4–1/2 as long as the adjacent lemma; paleas eventually disarticulating with the rest of the spikelet, leaving the naked axis	14 Eragrostis pilosa
+	Lower glume 2/3 to about as long as the adjacent lemma; paleas persistent on the rachilla after the lemmas and fruits have disarticulated	(14)

14 (13)	Flowering stems with a row of small, resinous glands (appearing as irregular bumps or shallow pits) below at least some of the nodes, these often fused into a glandular ring; spikelets 5–11 mm long	1 Eragrostis barrelieri
+	Flowering stems without resinous glands below the nodes; spikelets 1.5–7.5 mm long	(15)

15 (14)	Spikelets mostly spreading along the inflorescence branches; fruits broadly elliptic to nearly circular in outline; inflorescences elliptic in outline, broadest near the middle; spikelets 1.5–5.5 mm long, with 2–9 florets	7 Eragrostis frankii
+	Spikelets appressed to the inflorescence branches or nearly so (spreading in the uncommon var. miserrima); fruits ovate in outline; inflorescences ovate to triangular in outline, broadest below the middle; spikelets 3.5–11 mm long, with (3–)6–20 florets	13 Eragrostis pectinacea

16 (12)	Spikelets appressed to the inflorescence branches or nearly so	(17)
+	Spikelets mostly spreading along the inflorescence branches	(18)

17 (16)	Leaf blades 2.5–5.0 mm wide, flat or the margins loosely inrolled; leaf sheaths and inflorescences usually sticky when fresh; basal leaves only slightly longer than those of the stems, straight or slightly curved, but not arched toward the ground; upper glume 1–2 mm long; anthers 0.2–0.4 mm long; fruits 0.6–0.9 mm long	4 Eragrostis curtipedicellata
+	Leaf blades 1.5–3.0 mm wide, the margins strongly inrolled; plants not sticky; basal leaves noticeably longer than those of the stems, conspicuously arched toward the ground; upper glume 2–3 mm long; anthers 0.9–1.5 mm long	5 Eragrostis curvula

18 (16)	Lemmas rounded to bluntly angled on the back, not keeled, the lateral nerves faint	(19)
+	Lemmas keeled on the back, the lateral nerves relatively conspicuous	(20)

19 (18)	Leaf sheaths hairy at the tip and margins, sometimes also on the surface; spikelets 2–4 mm long, with 2–6 florets; fruits without a longitudinal groove	9 Eragrostis hirsuta
+	Leaf sheaths with a line of hairs at the tip and occasionally also along the margins near the tip, otherwise glabrous; spikelets (3–)4–7 mm long, with (2–)5–11 florets; fruits with a noticeable, longitudinal groove	11 Eragrostis intermedia Hitchc. var. intermedia

20 (18)	Main branches of the inflorescence with the axes smooth and glabrous or rarely with a few hairs in the axils of the main branches (roughened toward the branch tips and on the spikelet stalks); anthers 0.9–1.6 mm long; fruits with a noticeable, longitudinal groove	18 Eragrostis trichodes
+	Branches of the inflorescence with the axes roughened and with small tufts of hair in the axils of the main branches; anthers 0.3–0.5 mm long; fruits without a longitudinal groove	(21)

21 (20)	Leaf blades 2–4 mm wide; spikelets on long stalks, these hairlike, fragile, and not stiff; plants with the base hardened, but not knotty, without rhizomes	6 Eragrostis elliottii
+	Leaf blades 3–8 mm wide; spikelets on short to long stalks, these slender but stiff; plants with the base knotty, often with short rhizomes	17 Eragrostis spectabilis