Panicum, L

Vorontsova, Maria S., 2018, Revision of the group previously known as Panicum L. (Poaceae: Panicoideae) in Madagascar, Candollea 73 (2), pp. 143-186 : 145-147

Key to Panicum s.l. in Madagascar

1. Most spikelets more than 2 mm long .......................... 2

1a. Most spikelets less than 2 mm long ........................... 18

2. Culms mostly erect, plants in tufts, most leaves basal, growing in dry places and open habitats, not high montane ...................................................................... 3

2a. Plants prostrate or scrambling or climbing, most leaves positioned on the culms, growing in forest understory, wet habitats, or high montane habitats ........................ 9

3. Upper lemma rugose, common invasive plant across Madagascar .................................................... 32. U. maxima

3a. Upper lemma smooth .................................................. 4

4. Lower glume ¼ of the spikelet length, 1-veined, culms spongy, common plant of cultivated areas ...................... .............................................................25. P. subalbidum

4a. Lower glume ½–3/4 as long as the spikelet, 3–7-veined, culms not spongy ......................................................... 5

5. Spikelets 3–4 mm long and apically obtuse, rare plant from N Madagascar................................ 4. P. ankarense

5a. Spikelets 2–3 mm long and apically acute or acuminate ... ..................................................................................... 6

6. Glumes and the lower lemma apically long-acuminate, turned outwards at maturity ........................................ 7

6a. Glumes and the lower lemma acute to shortly acuminate, not turned outwards at maturity .................................. 8

7. Perennial with glabrous stems and nodes ....................... ............................................................. 11. P. dregeanum

7a. Annual with pilose stems and nodes (if glabrous annual cf. P. humile ) ...................................... 20. P. novemnerve

8. Spikelets almost always subtended by long white cilia, all leaves basal, spikelets acuminate ................ 7. P. cinctum

8a. Pedicels glabrous, plant usually geniculately ascending, leaves at the base and along the culms, spikelets acute ... ................................................................. 17. P. luridum

9. Lower glume (almost) as long as the spikelet, the spikelets acuminate .................................................................. 10

9a. Lower glume shorter than the spikelet, rounded to acute ................................................................................... 11

10. Panicle open, spikelets 2–2.5(–2.7) mm long .................. ........................................................... 2. P. ambositrense

10a. Panicle contracted (linear to narrowly ovate), spikelets 2.5–3(–3.2) mm long ............................... 22. P. perrieri

11. Gland-tipped hairs on the inflorescence visible with a hand lens, growing close to water ...... 1. A. hymeniochila

11a. Inflorescence lacking gland-tipped hairs, not associated with water ................................................................. 12

12. Spikelets oblong, subtended by long white cilia, lower glume with no veins, less than 1/3 of the spikelet length .. .......................................................... 27. P. trichocladum

12a. Spikelets elliptic to ovate, not subtended by cilia, lower glume with 3–5 veins, 1/3–3/4 as long as the spikelet .... 13

13. Spikelets asymmetric with the lower glume attached c. 0.5 mm below the upper glume; spikelets brown; plant of lowland forest understory ............... 23. P. pleianthum

13a. Spikelets symmetric, the lower glume not clearly separated from the rest of the spikelet; spikelets white to purple or brown; plants of mid to high elevations ..... 14

14. Leaves less than 2 mm wide, less than 3 cm long, high elevation plants from Andringitra ............................. 15

14a. Leaves more than 2 mm wide ................................... 16

15. Leaves imbricate, 0.5–3 × 0.5–2 mm, the spikelets terminal, rare and difficult to find, single at branch apices or rarely up to three together ............... 9. P. cupressifolium

15a. Leaves not imbricate, 4–30 × 1– 2 mm, inflorescences terminal, fully exserted on a peduncle 6 –20 cm long, 1.5–4(–7) cm long, obovate, few-flowered ....................... ....................................................... 24. P. spergulifolium

16. Inflorescence branches spreading at maturity ................. ........................................................ 3. P. andringitrense

16a. Inflorescence branches ascending or appressed ......... 17

17. Spikelets single, the upper lemma without apical crest, common species of the high plateau ........ 17. P. luridum

17a. Spikelets paired, the upper lemma with an apical crest, rare plant from Andringitra ............. 21. P. palackyanum

18. Lower glume as long as the spikelet or slightly longer, spikelets usually with long trichomes ........................ 19

18a. Lower glume shorter than the spikelet, spikelets usually glabrous ..................................................................... 22

19. Leaves rolled, plant caespitose and erect, most leaves at base ............................................... 30. T. brazzavillense

19a. Leaves flat or rolled, plant prostrate or scrambling on rocks, significant proportion of the leaves cauline ..... 20

20. Leaves ovate, often cordate at base, upper lemma smooth, common understory plant ................... 5. P. brevifolium

20a. Leaves linear, elliptic, or lanceolate, not cordate at base, upper lemma with verrucae, endemic of the high plateau ................................................................................... 21

21. Upper lemma verrucae elongated, rare annual ................ ................................................................ 6. P. capuronii

21a. Upper lemma verrucae round, common on the high plateau, vegetatively variable annual or perennial ........... ............................................................. 26. P. subhystrix

22. Lower glume nerveless or with one vein ................... 23

22a. Lower glume with 3–5 veins ..................................... 28

23. Spikelets drying translucent white, 0.9–1.1(–1.3) mm long ................................................................................... 24

23a. Spikelets drying pale yellowish to purple, 1.1–1.7 mm long ................................................................................... 25

24. Mature leaves with no auricles, upper glume and lower lemma with white bulbous crystal-like prickle hairs ...... ............................................................. 8. P. crystalinum

24a. Mature leaves with auricles 1–1.5 mm long, upper lemma and lower lemma glabrous or with small prickle hairs .... .................................................... 18. P. manongarivense

25. Panicles open at maturity, at least some spikelets single. ................................................................................... 26

25a. Panicles or groups of spikelets condensed, with no single spikelets ..................................................................... 27

26. Mostly erect plants of drier areas, inflorescence branches and spikelets purple to dark brown ......... 12. P. flacourtii

26a. Prostrate plants of wet areas, inflorescence branches and spikelets pale ....................................... 29. P. vohitrense

27. Spikelets evenly distributed throughout the panicle ....... ................................................................. 10. P. danguyi

27a. Spikelets forming a globose head at the apices of panicle branches ................................................... 19. P. mitopus

28. Culms mostly erect, plants in tufts, most leaves basal ................................................................................... 29

28a. Plants prostrate or scrambling or climbing, most leaves positioned on the culms ............................................ 32

29. Annual, spikelets acuminate, glumes turning outwards at maturity (spikelets yawning), NW Madagascar (if perennial with acuminate spikelets cf. P. dregeanum ) ............... ................................................................... 14. P. humile

29a. Perennial, spikelets rounded to acute, glumes not turning outwards at maturity (spikelets not yawning) ............ 30

30. Spikelets pilose, lower glume rounded on the back, 3/4–4/5 as long as the spikelet ................... 30. T. brazzavillense

30a. Spikelets glabrous, lower glume keeled, ½ as long as the spikelet ...................................................................... 31

31. Spikelets apically acute, 1.8–2.5 mm long, high plateau ................................................................. 17. P. luridum

31a. Spikelets apically rounded, 1.3–1.7 mm long, coastal areas ........................................................... 28. P. voeltzkowii

32. Leaves more than 1 cm wide, spikelets drying dark brown, forest understory climber with inflorescence branches dehiscent at maturity, North Madagascar....................... .............................................................. 13. P. humbertii

32a. Leaves less than 1 cm wide, spikelets drying green, purple, or light brown, not a forest understory climber, inflorescence branches not dehiscent .................................... 33

33. Leaves glaucous, usually appressed to the stem or retrorse, inflorescence branches spreading on a partly exserted panicle, common creeping plant ........ 31. T. parvifolium

33a. Leaves not glaucous, usually not appressed or retrorse, panicles usually fully exserted .................................... 34

34. Spikelets asymmetric with the lower glume attached c. 0.5 mm below the upper glume; spikelets brown; plant of forest understory ............................ 23. P. pleianthum

34a. Spikelets symmetric, the lower glume not clearly separated from the rest of the spikelet; spikelets white to purple or brown; plants usually of open areas ............ 35

35. Annual, leaf blades elliptic ............... 16. P. inconspicuum

35a. Perennial, leaf blades linear to lanceolate ................... 36

36. Panicle 10–20 cm long, lower glume rounded on the back, 3/4–4/5 as long as the spikelet, tapia vegetation ................. .................................................................. 15. P. ibitense

36a. Panicle 2–7 cm long, lower glume keeled, c. ½ as long as the spikelet, open areas .............................................. 37

37. Spikelets apically acute, 1.8–2.5 mm long; high plateau ................................................................. 17. P. luridum

37a. Spikelets apically rounded, 1.3–1.7 mm long; coastal areas ............................................................ 28. P. voeltzkowii