KEY TO THE SPECIES OF HORDEUM

1. Auricles large, well-developed, also the upper ones. Glumes of central spikelet distinctly flattened; body of lateral spikelets at least 10 mm long

2

2. Perennial, with a bulbous swelling at the base. Lateral spikelets with awns up to 2 mm long

H. bulbosum, p. 29

2. Annual, without a bulbous swelling at the base. Lateral spikelets without awns or with awns 2-15 cm long

3

3. Central spikelet sessile, 3 mm or more wide, awn if present 5-15 cm

H. vulgare, p.23

3. Central spikelet pedicellate to subsessile (to sessile), 2 mm or less wide, awn 2-4 cm

H. murinum, p.33

1. Auricles generally lacking, although sometimes present in the lower leaves, and then inconspicuous. Glumes of central spikelet setaceous or flattened; body of lateral spikelets 5 mm or less

4

4. Plants annual

5

5. Glumes of central spikelet 1.5-4 cm

6

6. Glumes strongly spreading at maturity

7

7. Glumes of central spikelet more or less flattened, 1.5-2 cm

H. arizonicum, p. 65

7. Glumes of central spikelet not flattened, usually much longer than 2 cm

H. jubatum, p. 63

6. Glumes not strongly spreading at maturity

H. marinum, p. 73

5. Glumes of central spikelet less than 1.5 cm

8

8. Lateral spikelets with awns 5-10 mm long

H. marinum, p. 73

8. Lateral spikelets without awns or awns up to 1-2 mm long

9

9. Glumes of central spikelet setaceous or somewhat flattened

H. depressum, p.99

9. Glumes of central spikelet distinctly flattened

10

10. Tuft dense or loose, with fibrous sheaths. Lemma awn of central spikelet less than 5 mm; glumes usually less than 9 mm; flattened part of the lower glume of lateral spikelets often with distinct shoulders or teeth. Rachilla more or less flattened

H. flexuosum, p.45

10. Tuft loose, without fibrous sheaths. Lemma awn of central spikelet more than 5 mm; glumes usually much longer than 9 mm; flattened part of the lower glume of lateral spikelets without distinct shoulders or teeth. Rachilla terete

11

11. Lateral spikelets 2.8-5.7 mm (excl. awn), aristulate to aristate (rarely muticous). Glumes not spreading at the fruiting stage

H. pusillum, p.39

11. Lateral spikelets 1.7-4.4 mm, obtuse, acute to muticous (rarely). Glumes usually spreading at the fruiting stage

12

12. Culm nodes glabrous, only lower (sometimes also middle) leaf sheaths pubescent. Lower glume of lateral spikelets more than 0.4 mm wide, upper one setaceous

H. euclaston, p.43

12. Culm nodes and leaf sheaths more or less pubescent. Lower glume of lateral spikelets less than 0.4 mm wide, upper one often flattened (sometimes setaceous)

H. intercedens, p. 41

4. Plants perennial

13

13. Glumes of central spikelet distinctly flattened in the lower part

14

14. Glumes spreading at the fruiting stage

15

15. Glumes scabrid; lower glume of lateral spikelets distinctly flattened at the base, with a sharp demarcation line at the base. Rachilla thick, flat

H. chilense, p.49

15. Glumes somewhat hairy; lower glume of lateral spikelets not distinctly flattened at the base and with no sharp demarcation line at the base. Rachilla thin, setaceous

H. arizonicum, p.65

14. Glumes not spreading at the fruiting stage

16

16. Lemma with 7 or 9 (rarely 5) conspicuous nerves

H. cordobense, p. 51

16. Lemma with 5 (rarely more) inconspicuous nerves

17

17. Lemma glabrous

18

18. Flattened part of the lower glume of lateral spikelets often with distinct shoulders or teeth

H. flexuosum, p.45

18. Flattened part of lower glume of lateral spikelets without distinct shoulders or teeth

19

19. Awn of lemma 1-2 mm. Rachilla thin, setaceous

H. patagonicum, p.111

19. Awn of lemma 5-10 mm. Rachilla thick, flattened

H. chilense, p.49

17. Lemma pubescent, at least in the apical half

20

20. The lower glume of lateral spikelets distinctly flattened; spike pale green; rachilla more or less thick. The whole lemma pubescent (rarely glabrous)

H. stenostachys, p.53

20. The lower glume of lateral spikelets only somewhat flattened to more or less setaceous; spike purple or bluish; rachilla thin or missing. Only the upper half of the lemma scabrid-hairy (rarely the whole lemma pubescent)

H. muticum, p.47

13. Glumes of central spikelet not flattened in the lower part

21

21. Glumes spreading at the fruiting stage

22

22. Central spikelet with a short awn, 4-8 mm

23

23. Lemma and palea 4-5.5 mm; lemma awn distinctly subulate

H. roshevitzii, p.85

23. Lemma and palea 6.5-9.5 mm; lemma awn not distinctly subulate

H. fuegianum, p.107

22. Central spikelet with a long awn, 1 cm or more

24

24. Glumes of central spikelet more or less flattened

H. arizonicum, p.65

24. Glumes of central spikelet not flattened

25

25. Lateral spikelets aristate, the awns 1.5-3 cm, more than half as long as the glumes

H. comosum, p.59

25. Lateral spikelets acute to shortly aristate, the awns never more than 1.5 cm, less than half as long as the glumes

26

26. Lemma of central spikelet scabrid. Spike long, more or less terete, greenish

H. procerum, p.67

26. Lemma of central spikelet glabrous or scabrid-hairy only in the upper part. Spike rather short, terete or laterally compressed, often purplish coloured

27

27. Spike terete or more or less laterally compressed. Glumes 1-2.5 cm, glumes and lateral spikelets glabrous to scabrid to conspicuously hairy

28

28. Spike greenish, terete. Lemma and glumes glabrous or shortly scabrid

H. capense, p.81

28. Spike reddish or black purple, more or less laterally compressed. Glumes scabrid to distinctly pubescent, lemma scabrid or pubescent in the upper part (or glabrous)

29

29. Triplet often more than 2 cm. Lemma of central spikelet 7-10 mm. Rachilla about as long as the palea. Spike often blackish purple

H. pubiflorum, p.55

29. Triplet often less than 2 cm. Lemma of central spikelet 5-7 mm. Rachilla usually less than half as long as the palea. Spike often reddish

H. halophilum, p.57

27. Spike not laterally compressed. Glumes 2.5-7 cm, glumes and lateral spikelets usually not hairy

30

30. Lateral spikelets aristulate, 7-15 mm. Anthers 1-1.5 mm

H. lechleri, p.71

30. Lateral spikelets shortly aristulate, 4-6 mm. Anthers 0.6-1 mm

H. jubatum, p. 63

21. Glumes not spreading at the fruiting stage

31

31. Culms very short, usually less than 15-20 cm

H. patagonicum, p.111

31. Culms long, usually more than 30 cm

32

32. Anthers more than (2.7-3)mm

33

33. Lemma awn of central spikelet more than 6 mm, glumes of central spikelet usually more than 10 mm

H. secalinum, p.79

33. Lemma awn of central spikelet less than 5 mm, glumes of central spikelet up to 10 mm

34

34. Culm nodes hairy or glabrous; anthers always hanging freely at anthesis; selfsterile; lateral spikelets usually with a distinct, short awn (up to 3 mm); Asia

H. brevisubulatum, p.87

34. Culm nodes glabrous; anthers emerging but not all hanging freely at anthesis; self fertile; lateral spikelets obtuse to acute, not aristate; South America

H. tetraploidum, p.105

32. Anthers less than (2.7-)3 mm long

35

35. Lemma more or less pubescent

36

36. Rachis usually not brittle. Lemma with short, more or less sparse hairs, awn of lemma more than 5 mm

H. bogdanii, p.83

36. Rachis brittle. Lemma with obtuse long hairs, awn of lemma less than 5 mm

H. patagonicum, p.111

35. Lemma glabrous

37

37. Central glumes long, 7-15 mm, central awn 1.5-8 mm

H. parodii, p.109

37. Central glumes long, 8-23 mm, central awn long, 7-21 mm or: Central glumes short, 5-9 mm, central awn short, 2.5-8.5 mm

38

38. Caespitose. Central glumes long, 8-23 mm, central awn long, 7-21 mm

39

39. Leaf narrow, glaucous, erect. Spike glaucous, laterally compressed

H. erectifolium, p.103

39. Leaf not narrow, or glaucous, or erect. Spike not glaucous, nor laterally compressed

40

40. Central glumes (13-23 mm) about the length of the lateral ones, approaching that of the central spikelet including awn (16-31 mm); lateral lower glume more or less flattened in the basal part

H. capense, p.81

40. Central glumes (7-17 mm) shorter than the lateral ones, approaching the length of the body of the lemma (7-10 mm; lemma including awn 12-22 mm); lateral lower glume setaceous in the basal part

H. brachyantherum, p.93

38. Tufts somewhat rhizomatous. Central glumes short, 5-9 mm, central awn short, 2.5-8.5 mm

H. guatemalense, p.101

1. Auricles large, well-developed, also the upper ones. Glumes of central spikelet distinctly flattened; body of lateral spikelets at least 10 mm long					2
	2. Perennial, with a bulbous swelling at the base. Lateral spikelets with awns up to 2 mm long				H. bulbosum, p. 29
	2. Annual, without a bulbous swelling at the base. Lateral spikelets without awns or with awns 2-15 cm long				3
	3. Central spikelet sessile, 3 mm or more wide, awn if present 5-15 cm				H. vulgare, p.23
	3. Central spikelet pedicellate to subsessile (to sessile), 2 mm or less wide, awn 2-4 cm				H. murinum, p.33
1. Auricles generally lacking, although sometimes present in the lower leaves, and then inconspicuous. Glumes of central spikelet setaceous or flattened; body of lateral spikelets 5 mm or less					4
4. Plants annual					5
	5. Glumes of central spikelet 1.5-4 cm				6
			6. Glumes strongly spreading at maturity		7
				7. Glumes of central spikelet more or less flattened, 1.5-2 cm	H. arizonicum, p. 65
7. Glumes of central spikelet not flattened, usually much longer than 2 cm					H. jubatum, p. 63
			6. Glumes not strongly spreading at maturity		H. marinum, p. 73
	5. Glumes of central spikelet less than 1.5 cm				8
	8. Lateral spikelets with awns 5-10 mm long				H. marinum, p. 73
	8. Lateral spikelets without awns or awns up to 1-2 mm long				9
	9. Glumes of central spikelet setaceous or somewhat flattened				H. depressum, p.99
	9. Glumes of central spikelet distinctly flattened				10
	10. Tuft dense or loose, with fibrous sheaths. Lemma awn of central spikelet less than 5 mm; glumes usually less than 9 mm; flattened part of the lower glume of lateral spikelets often with distinct shoulders or teeth. Rachilla more or less flattened				H. flexuosum, p.45
	10. Tuft loose, without fibrous sheaths. Lemma awn of central spikelet more than 5 mm; glumes usually much longer than 9 mm; flattened part of the lower glume of lateral spikelets without distinct shoulders or teeth. Rachilla terete				11
	11. Lateral spikelets 2.8-5.7 mm (excl. awn), aristulate to aristate (rarely muticous). Glumes not spreading at the fruiting stage				H. pusillum, p.39
	11. Lateral spikelets 1.7-4.4 mm, obtuse, acute to muticous (rarely). Glumes usually spreading at the fruiting stage				12
	12. Culm nodes glabrous, only lower (sometimes also middle) leaf sheaths pubescent. Lower glume of lateral spikelets more than 0.4 mm wide, upper one setaceous				H. euclaston, p.43
	12. Culm nodes and leaf sheaths more or less pubescent. Lower glume of lateral spikelets less than 0.4 mm wide, upper one often flattened (sometimes setaceous)				H. intercedens, p. 41
4. Plants perennial					13
13. Glumes of central spikelet distinctly flattened in the lower part					14
	14. Glumes spreading at the fruiting stage				15
		15. Glumes scabrid; lower glume of lateral spikelets distinctly flattened at the base, with a sharp demarcation line at the base. Rachilla thick, flat			H. chilense, p.49
		15. Glumes somewhat hairy; lower glume of lateral spikelets not distinctly flattened at the base and with no sharp demarcation line at the base. Rachilla thin, setaceous			H. arizonicum, p.65
	14. Glumes not spreading at the fruiting stage				16
	16. Lemma with 7 or 9 (rarely 5) conspicuous nerves				H. cordobense, p. 51
	16. Lemma with 5 (rarely more) inconspicuous nerves				17
	17. Lemma glabrous				18
	18. Flattened part of the lower glume of lateral spikelets often with distinct shoulders or teeth				H. flexuosum, p.45
	18. Flattened part of lower glume of lateral spikelets without distinct shoulders or teeth				19
	19. Awn of lemma 1-2 mm. Rachilla thin, setaceous				H. patagonicum, p.111
	19. Awn of lemma 5-10 mm. Rachilla thick, flattened				H. chilense, p.49
	17. Lemma pubescent, at least in the apical half				20
	20. The lower glume of lateral spikelets distinctly flattened; spike pale green; rachilla more or less thick. The whole lemma pubescent (rarely glabrous)				H. stenostachys, p.53
	20. The lower glume of lateral spikelets only somewhat flattened to more or less setaceous; spike purple or bluish; rachilla thin or missing. Only the upper half of the lemma scabrid-hairy (rarely the whole lemma pubescent)				H. muticum, p.47
13. Glumes of central spikelet not flattened in the lower part					21
21. Glumes spreading at the fruiting stage					22
	22. Central spikelet with a short awn, 4-8 mm				23
	23. Lemma and palea 4-5.5 mm; lemma awn distinctly subulate				H. roshevitzii, p.85
	23. Lemma and palea 6.5-9.5 mm; lemma awn not distinctly subulate				H. fuegianum, p.107
	22. Central spikelet with a long awn, 1 cm or more				24
	24. Glumes of central spikelet more or less flattened				H. arizonicum, p.65
	24. Glumes of central spikelet not flattened				25
	25. Lateral spikelets aristate, the awns 1.5-3 cm, more than half as long as the glumes				H. comosum, p.59
	25. Lateral spikelets acute to shortly aristate, the awns never more than 1.5 cm, less than half as long as the glumes				26
	26. Lemma of central spikelet scabrid. Spike long, more or less terete, greenish				H. procerum, p.67
	26. Lemma of central spikelet glabrous or scabrid-hairy only in the upper part. Spike rather short, terete or laterally compressed, often purplish coloured				27
	27. Spike terete or more or less laterally compressed. Glumes 1-2.5 cm, glumes and lateral spikelets glabrous to scabrid to conspicuously hairy				28
			28. Spike greenish, terete. Lemma and glumes glabrous or shortly scabrid		H. capense, p.81
			28. Spike reddish or black purple, more or less laterally compressed. Glumes scabrid to distinctly pubescent, lemma scabrid or pubescent in the upper part (or glabrous)		29
			29. Triplet often more than 2 cm. Lemma of central spikelet 7-10 mm. Rachilla about as long as the palea. Spike often blackish purple		H. pubiflorum, p.55
			29. Triplet often less than 2 cm. Lemma of central spikelet 5-7 mm. Rachilla usually less than half as long as the palea. Spike often reddish		H. halophilum, p.57
	27. Spike not laterally compressed. Glumes 2.5-7 cm, glumes and lateral spikelets usually not hairy				30
	30. Lateral spikelets aristulate, 7-15 mm. Anthers 1-1.5 mm				H. lechleri, p.71
	30. Lateral spikelets shortly aristulate, 4-6 mm. Anthers 0.6-1 mm				H. jubatum, p. 63
21. Glumes not spreading at the fruiting stage					31
	31. Culms very short, usually less than 15-20 cm				H. patagonicum, p.111
	31. Culms long, usually more than 30 cm				32
32. Anthers more than (2.7-3)mm					33
	33. Lemma awn of central spikelet more than 6 mm, glumes of central spikelet usually more than 10 mm				H. secalinum, p.79
	33. Lemma awn of central spikelet less than 5 mm, glumes of central spikelet up to 10 mm				34
	34. Culm nodes hairy or glabrous; anthers always hanging freely at anthesis; selfsterile; lateral spikelets usually with a distinct, short awn (up to 3 mm); Asia				H. brevisubulatum, p.87
	34. Culm nodes glabrous; anthers emerging but not all hanging freely at anthesis; self fertile; lateral spikelets obtuse to acute, not aristate; South America				H. tetraploidum, p.105
32. Anthers less than (2.7-)3 mm long					35
	35. Lemma more or less pubescent				36
			36. Rachis usually not brittle. Lemma with short, more or less sparse hairs, awn of lemma more than 5 mm		H. bogdanii, p.83
	36. Rachis brittle. Lemma with obtuse long hairs, awn of lemma less than 5 mm				H. patagonicum, p.111
	35. Lemma glabrous				37
	37. Central glumes long, 7-15 mm, central awn 1.5-8 mm				H. parodii, p.109
	37. Central glumes long, 8-23 mm, central awn long, 7-21 mm or: Central glumes short, 5-9 mm, central awn short, 2.5-8.5 mm				38
	38. Caespitose. Central glumes long, 8-23 mm, central awn long, 7-21 mm				39
			39. Leaf narrow, glaucous, erect. Spike glaucous, laterally compressed		H. erectifolium, p.103
			39. Leaf not narrow, or glaucous, or erect. Spike not glaucous, nor laterally compressed		40
			40. Central glumes (13-23 mm) about the length of the lateral ones, approaching that of the central spikelet including awn (16-31 mm); lateral lower glume more or less flattened in the basal part		H. capense, p.81
			40. Central glumes (7-17 mm) shorter than the lateral ones, approaching the length of the body of the lemma (7-10 mm; lemma including awn 12-22 mm); lateral lower glume setaceous in the basal part		H. brachyantherum, p.93
	38. Tufts somewhat rhizomatous. Central glumes short, 5-9 mm, central awn short, 2.5-8.5 mm				H. guatemalense, p.101