Avenula (Dumort.) Dumort.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1980, Flora Europaea. Volume 5. Alismataceae to Orchidaceae (Monocotyledones), Cambridge: Cambridge University Press : 210-211

62. Avenula (Dumort.) Dumort. 1

Like Helictotrichon but roots without a ring of sclerenchyma surrounding the endodermis; basal leaves without ribs above, with 2 distinct lines of bulliform cells along the mid-vein above; ligule of cauline leaves acute; spikelets erect, with 2-7 fertile florets; lower glume (l-)3-veined, the upper 3(-5)-veined; awn twisted and usually compressed in lower part.

Measurements of the width of the stem refer to its thickness in the lower | and the length of the ligule of cauline leaves refers to the uppermost leaf, unless this leaf is exceptionally short. Spikelet-length excludes the awns, the number of florets includes sterile rudimentary florets and the length of rhachilla-segments and of their hairs refers to the segment between the first and second florets. Glume-length is measured on a lateral spikelet and characters of the lemma refer to the first and second florets at anthesis.

The treatment of species from S. Europe and particularly from Spain is provisional and further investigation is required.

Literature: C. Gervais, Denkschr. Schweiz. Naturf. Ges. 88: 3-166 (1973). J. Holub, Acta Horti Bot. Prag. 1962: 75-86 (1962); Acta Mus. Nation. Prag. 17(B), 1961(5): 189-244 (1962). E. Paunero, Anal. Inst. Bot. Cavanilles 17(1): 267-283 (1959). W. Sauer & H. Chmelitschek, Mitt. Bot. Staatssamm. (München) 12: 513-607 (1976). A. St-Yves, Candollea 4: 423-490 (1931). 1 Lower part of awn terete, of uniform thickness when viewed from the side; keels of palea glabrous and smooth; veins not reaching upper margin of lemma 1. pubescens 1 Lower part of awn flattened, alternately thick and thin when viewed from the side; keels of palea shortly ciliate or aculeolate; veins reaching upper margin of lemma 2 Basal leaves in cross-section with a continuous subepidermal layer of sclerenchyma beneath; rhachilla-segments with hairs 2-5-4 mm 27. hackelii 2 Basal leaves in cross-section without a continuous subepidermal layer of sclerenchyma beneath; rhachillasegments glabrous or with hairs not more than 3 mm 3 Rhachilla-segments glabrous or with sparse hairs near apex, the hairs shorter than those of the callus 4 Lemma sericeous or hairy on the back in the lower | 5 Basal leaves deeply sulcate beneath; uppermost cauline leaf 3-8 cm, patent; lower glume 10-12 mm, the upper 12-16 mm 24. gervaisii 5 Basal leaves not sulcate beneath; uppermost cauline leaf not more than 1-5 cm, appressed to stem; lower glume 6-9 mm, the upper 8-11 mm 6 Basal leaves 1-5-3 mm wide, V-shaped in cross-section, spirally twisted when dead, ±sm ooth; cartilaginous margin and mid-vein distinct beneath 19. bromoides 6 Basal leaves 0-3-0-4 mm wide, orbicular in cross-section, not spirally twisted when dead, scabrid; cartilaginous margin and mid-vein not distinct beneath 20. murcica 4 Lemma not sericeous or hairy on the back in the lower | 7 Lateral veins of basal leaves connected by sclerenchyma and colourless parenchyma with at least 1 leaf-surface 8 Lemma reddish-brown, longitudinally sulcate in the lower half 9 Basal leaves 2-5 mm wide, not sulcate beneath, and with 4-6 sclerenchyma-strands on each side of midvein; callus-hairs 0-5-1 mm 9. compressa 9 Basal leaves 0-3-2(-2-5) mm wide, sulcate beneath, and with l(-3) sclerenchyma-strands on each side of midvein; callus-hairs 1-5-2-5 mm 12. mirandana 8 Lemma greenish-yellow, not longitudinally sulcate 10 Basal leaves not sulcate beneath; callus-haiis c. 1 mm; panicle with 7-17 spikelets 13. gonzaloi 10 Basal leaves sulcate beneath; callus-hairs 1-5-2-5 mm; panicle with 3-10 spikelets 12. mirandana 7 Lateral veins of basal leaves separated from subepidermal sclerenchyma by chlorenchyma 11 Basal leaves flat or conduplicate, the cross-section oblong in outline 12 Basal leaves not sulcate beneath; subepidermal sclerenchyma groups small or almost absent; callushairs 0-4-0-8 mm 19. bromoides 12 Basal leaves sulcate beneath; subepidermal sclerenchyma groups present opposite all veins; callushairs c. 1-5 mm 13 Spikelets 18-24 mm, with 5-7 florets; lemma narrowed from the middle, acute; anthers 5-6 mm 21. cincinnata 13 Spikelets (20-)25-30mm, with 7-9 florets; lemma narrowed in the upper |, subtruncate; anthers 6-8 mm 22. peloponnesiaca 11 Basal leaves usually setaceous or junciform, the crosssection elliptical to orbicular in outline 14 Basal leaves 1-2 mm in diameter, junciform; lemma narrowed from the middle

15 Basal leaves 1-1-5 mm in diameter, deeply sulcate; panicle 7-15 cm 25. pruinosa 15 Basal leaves 1 -5-2 mm in diameter, smooth or slightly sulcate; panicle 15-22 cm 26. crassifolia 14 Basal leaves O-3-O- 8 mm in diameter, setaceous; lemma narrowed in the upper |

16 Basal leaves 10-40 cm, deeply sulcate, the upper cauline at least 3 cm; panicle with 13-21 spikelets; lower glume 10-12 mm 24. gervaisii 16 Basal leaves 2-7 cm, not sulcate, the upper cauline

not more than 1 cm; panicle with 2-8 spikelets; lower glume 7-8 mm 20. murcica 3 Rhachilla-segments hairy at least in the upper |, the hairs longer than or about as long as those of the callus

17 Ligulesofbasalandcaulineleavesofaboutthesame

length

18 Densely caespitose; lateral veins of basal leaves not connected with the epidermis by sclerenchyma; ligule

of basal leaves 2- 3 mm 23. cycladum 18 Stoloniferous; lateral veins of basal leaves connected with the epidermis by sclerenchyma; ligule of basal leaves 4-6 mm 10. aetolica 17 Liguleof caulineleavesusuallyat leasttwiceaslongas

that of the basal leaves

19 Lateral veins of basal leaves not connected with the epidermis by sclerenchyma (S. Aegean region)

23. cycladum 19 Lateral veins of basal leaves connected with the epidermis

by sclerenchyma and colourless parenchyma

20 Lemma reddish-brown in lower i

21 Basal leaves 4-12 mm wide, their sheaths very strongly compressed 18. planiculmis 21 Basal leaves 0-4-6 mm wide, their sheaths terete to slightly compressed

22 Veins of lemma not excurrent; hairs of rhachillasegments 1 -1-5 mm 3. schelliana 22 Veins of lemma excurrent, forming 2(4) setae; hairs

of rhachilla-segments 1 -5-2-5 mm

23 Sheaths of basal leaves closed in the lower |(- |); lemma not longitudinally sulcate in the lower |; upper cauline leaf 2-7 cm, ± patent 2. versicolor 23 Sheaths of basal leaves closed at the base only; lemma longitudinally sulcate in the lower |; upper cauline leaf not more than 2 cm, appressed

to stem (4-7). marginata group 20 Lemma not reddish-brown in the lower |

24 Basal leaves 2-12 mm wide, their sheaths very strongly compressed

25 Basal leaves 4- 12 mm wide, with 8-16 lateral veins

on each side of the mid-vein; panicle often interrupted in the lower part 18. planiculmis 25 Basal leaves 2-6 mm wide, with 6-10 lateral veins on each side of the mid-vein; panicle usually not interrupted in the lower part 17. praeusta 24 Basal leaves 0-4- 6 mm wide, their sheaths terete or slightly compressed

26 Basal leaves convolute, setaceous to junciform, the cross-section elliptical to orbicular in outline

27 Basal leaves not more than i as long as stem, 1 - 5-

2 mm in diameter, very pungent, slightly sulcate; pedicels ± smooth; plant without stolons 15. pungens 27 Basal leaves | as long as stem, 0-4-1 -3 mm in diameter, not or only slightly pungent, not sulcate; pedicels scabrid; plant with short stolons

28 Stems 30- 60 cm, slender; ligule of upper cauline leaves 2-4 mm; basal leaves setaceous, 0-4-0-6

mm in diameter, with c. 3 lateral veins on each

side of the mid-vein; panicle 4-13 cm, with 4-9 spikelets 11. biavii 28 Stems 60- 100 cm, robust; ligule of upper cauline leaves 6-10 mm; basal leaves junciform, 1 -2-

1 - 3 mm in diameter; panicle 15-20 cm with 14- 17 spikelets 14. requienii 26 Basal leaves flat or conduplicate, the cross-section oblong to oblong-elliptical in outline

29 Basal leaves 2-7 cm

30 Basal leaves c. | as long as stem, 2-4 mm wide; spikelets 14-18 mm, with 5-7 florets; rhachillasegments with hairs 1-5-2-5 mm; upper glume 12-14 mm 8. levis 30 Basal leaves ~^2~'To as long as stem,0-8-2 mm wide; spikelets 10-12 mm, with 3-5 florets; rhachillasegments with hairs 0-4-1 mm; upper glume 9-10 mm (4-7). marginata group 29 Basal leaves 5-40 cm

31 Lemma longitudinally sulcate, at least at base, with

2(4) setae at apex; upper cauline leaf not more than 2 cm, appressed to stem

(4-7). marginata group 31 Lemma not longitudinally sulcate in lower i, without distinct setae at apex; upper cauline leaf usually more than 2 cm, patent

32 Spikelets 10-16 mm; rhachilla-segments 1-5-2 mm, with hairs 1-1-5 mm; upper glume 9-13 mm; anthers 3-5-4-5 mm 3. schelliana 32 Spikelets 12-23 mm; rhachilla-segments 2-3 mm, with hairs 2-3 mm; upper glume 12-18 mm; anthers 5-8 mm

33 Basal leaves 1-3 mm wide, usually conduplicate, with subterete sheaths; plant densely caespitose, usually without stolons; panicle with 5-18 spikelets 16. pratensis 33 Basal leaves 2-6 mm wide, usually flat, with compressed sheaths; plant laxly caespitose to ±creeping, with stolons; panicle with 12-30 spikelets 17. praeusta