Chrysopogon, Trinius, 1820

Tiwari, Arjun Prasad & Landge, Shahid Nawaz, 2022, Chrysopogon densipaniculatus (Poaceae: Andropogoneae): a new species from India, Phytotaxa 538 (3), pp. 241-248 : 246-247

Key to the species of Chrysopogon in India

1. Racemes short, reduced to a triad of 1 sessile and 2 pedicelled spikelets (rarely with 1–4 spikelet pairs in C. gryllus ); lower glume smooth, not tuberculated ....................................................................................................................................................................2

1. Racemes long, multi-spiculated; lower glume tuberculated ( Vetiveria group) ................................................................................22

2. Pedicels half as long as the sessile spikelets or longer.......................................................................................................................3

2. Pedicels shorter than half as long as the sessile spikelets ................................................................................................................15

3. Pedicels of the pedicelled spikelets glabrous or nearly so .................................................................................................................4

3. Pedicels of the pedicelled spikelets villous with rusty or pale hairs ..................................................................................................7

4. Culms creeping at the base; sessile spikelets 3.5–4.5 mm long; callus 3.0–6.0 mm long, decurrent, needle like......... C. aciculatus

4. Culms erect; sessile spikelets 5.0– 10 mm long; callus less than 2.5 mm long, not decurrent or needle like ....................................5

5. Panicle lax, bearing a few racemes; sessile spikelets 8.0– 10 mm long; geniculate awn 6.0–7.0 cm long ..................... C. castaneus

5. Panicle contracted, bearing several racemes; sessile spikelets 5.0–8.0 mm long; geniculate awn 2.5–5.0 cm long .........................6

6. Culms robust, more than 95 cm high; leaves sparsely pilose on ad-axial surface; lower glume of sessile spikelets with a row of black spicules on each side of the midrib; upper glume witharista ca. 6.5 mm long........................................................... C. gryllus

6. Culms slender, less than 95 cm high; leaves glabrous; lower glume of sessile spikelets minutely scaberulous-spinulose towards the truncate-notched apex; upper glume exaristate or shortly aristate from the notch................................................................. C. copei

7. Lower glume of pedicelled spikelet not awned..................................................................................................................................8

7. Lower glume of pedicelled spikelet awned......................................................................................................................................10

8. Leaves up to 2.0 mm broad; upper glume of pedicelled spikelet awned; awn of upper lemma of sessile spikelet more than 4.5 cm long............................................................................................................................................................................. C. tadulingamii

8. Leaves more than 3 mm broad; upper glume of pedicelled spikelet awnless; awn of upper lemma of sessile spikelet less than 4.0 cm long ...............................................................................................................................................................................................9

9. Basal sheaths silky; leaf bladesca. 50 cm long, glabrous; sessile spikelets ca. 5.0 mm long; pedicelled spikelets 4.0–5.0 mm long..................................................................................................................................................................... C. pseudozeylanicus

9. Basal sheaths glabrous; leaf bladesca. 30 cm long, pubescent or pilose; sessile spikelets 5.0–8.0 mm long; pedicelled spikelets 7.0– 15 mm long (longest in the genus) ................................................................................................................... C. nodulibarbis

10. Leaves conspicuously distichous, often plicate; sheaths much compressed at the basal, acutely keeled, often beset with bulbousbased bristles .......................................................................................................................................................................... C. asper

10. Leaves not conspicuously distichous; sheaths rounded on back not keeled ....................................................................................11

11. Leaf blades convolute, panicle less than 12 cm long ................................................................................................... C. narayaniae

11. Leaf blades flat; panicle more than 12 cm long ...............................................................................................................................12

12. Culms slender; leaf blades less than 25 cm long; sessile spikelets hispidulous, 7.5–9.0 mm long................................. C. orientalis

12. Culms robust; leaf blades more than 25 cm long; sessile spikelets glabrous, 6.0–7.0 mm long......................................................13

13. Leaf blades less than 10 mm wide, margins scabrous; panicle ovoid or lanceolate, very dense; pedicelled spikelets more than 10 mm long; lower glume of pedicelled spikelet with 10–12 mm long arista .................................................................... C. hamiltonii

13. Leaf blades more than 10 mm wide, margins spinulose; panicle oblong, dense; pedicelled spikelets less than 10 mm long; lower glume of pedicelled spikelet with 5.0–7.0 mm long arista...............................................................................................................14

14. Leaves linear with long white hairs; ligule an eciliate membrane; sessile spikelets lanceolate, callus hairs red ........ C. verticillatus

14. Leaves narrowly-lanceolate, glabrous; ligule a fringe of hairs; sessile spikelets oblong, callus hairs dark brown ....... C. lancearius

15. Leaves puberulous............................................................................................................................................................................16

15. Leaves glabrous, occasionally with few tubercle-based hairs, not puberulous................................................................................17

16. Sheaths not strongly laterally compressed; leaf blade less than 4.0 mm wide, margins tuberculate-ciliate; pedicelled spikelets 6.0– 10 mm long, usually both the glumes with 4.0–7.0 mm long awned (sometimes lower glume exaristate);callus base of sessile spikelets acute..................................................................................................................................................................... C. aucheri

16. Sheaths very strongly laterally compressed with a prominent keel; leaf blade more than 4.0 mm wide, margins spinulose; pedicelled spikelets 5.0 mm long, both glumes always muticous; callus base of sessile spikelets truncate ..................................... C. velutinus

17. Leaves conspicuously distichous; panicle interrupted .....................................................................................................................18

17. Leaves not distichous; panicle oblong, not interrupted ....................................................................................................................19

18. Callus densely bearded throughout; pedicel and callus brownish hairy; upper glume of the sessile spikelets aristate, with an arista 4.0–8.0 mm long................................................................................................................................................. C. purushothamanii

18. Callus densely bearded at the base only; pedicel and callusfulvous hairy; upper glume of the sessile spikelets exaristate................ ...................................................................................................................................................................................... C. polyphyllus

19. Pedicelled spikelets shorter than the sessile, hairs chocolate-brown or rufous-brown; lower glume of pedicelled spikelets muticous ............................................................................................................................................................................. C. hackelii

19. Pedicelled spikelets equal or longer than the sessile, hairs golden or golden-brown; lower glume of pedicelled spikelets aristate ... ..........................................................................................................................................................................................................20

20. Upper glume of the sessile spikelets with a prominent dorsal tuft of brown hairs ............................................................... C. fulvus

20. Upper glume of the sessile spikelets without a dorsal tuft of hairs (if hairy then slightly but not brownish)..................................21

21. Peduncle glandular; panicle very dense ca. 15 × 8.0 (–10) cm with 35–76 racemes from lower nodes; upper lemma of pedicelled spikelet bifid and its palea reduced (ca. 1.0 mm long), acute, bidentate or irregularly tri-cuspidate.................. C. densipaniculatus

21. Peduncle eglandular; panicle not dense, 3.0–15 × 1.0– 2.5 cm, racemes less than 30 from the lower nodes; upper lemma of pedicelled spikelet and its palea (if present then not reduced) with acute apices.......................................................................... C. serrulatus

22. Lower glume of pedicelled spikelets distinctly aristate .................................................................................................... C. lawsonii

22. Lower glume of pedicelled spikelets exaristate................................................................................................................................23

23. Roots aromatic; apex of upper glume of the sessile spikelets muticous; upper lemma muticous or briefly awned (awns less than 2.0 mm long, enclosed......................................................................................................................................................... C. zizanioides

23. Roots not aromatic; apex of upper glume of the sessile spikelets mucronate (mucro 0.4 mm long); second lemma awned (awns exerted, 2.5–3.0 cm long).............................................................................................................................................. C. festucoides