1	Annual	2
1	"Perennial herb"	6
2	"Lemma awned, awn 1--3 cm, lemma 2.5--6 mm"	3
2	"Lemma short-awned, awn < 1 mm, or awn 0; lemma < 2.5 mm"	4
3	"Lemma generally 4.5--6 mm; inflorescence generally < 1.5 cm wide, branches closely appressed; glumes generally 1--2 mm"	"Muhlenbergia appressa"
3	"Lemma generally 2.5--4.5 mm; inflorescence 1--5 cm wide, branches spreading to ascending; glumes generally < 1 mm"	"Muhlenbergia microsperma"
4	"Inflorescence narrow, < 1 cm wide; branches closely appressed; stems often rooting at lower nodes"	"Muhlenbergia filiformis"
4	"Inflorescence open, 1.5--8 cm wide; branches reflexed, ascending to spreading; stems not rooting at lower nodes"	5
5	"Inflorescence branches stiffly spreading to reflexed +- 90&deg; from axis; glumes glabrous; ligule teeth 2, 1 on each side"	"Muhlenbergia fragilis"
5	"Inflorescence branches ascending < 80&deg; from axis; glume tip short-hairy; ligule truncate to obtuse, irregularly short-toothed"	"Muhlenbergia minutissima"
6	"Lemma awn 0 or short-awned, awn < 1 mm"	7
6	"Lemma awn 1--30 mm"	13
7	"Inflorescence 5--14 cm wide, open, branches spreading"	"Muhlenbergia asperifolia"
7	"Inflorescence <= 4 cm wide, narrow, branches ascending to appressed, occasionally loosely spreading"	8
8	"Rhizomes creeping, +- scaly; stems +- decumbent to erect"	9
8	"Rhizomes 0; stems clumped or decumbent and +- rooting at nodes"	11
9	"Glumes 2.5--4 mm, +- = lemma; lower 1/2 lemma short-soft-hairy"	"Muhlenbergia californica"
9	"Glumes 0.5--1.8 mm, +- 1/2 lemma; lemma glabrous to +- scabrous"	10
10	"Ligule generally 1--2.5 mm; inflorescence axis generally obscured by branches, spikelets"	"Muhlenbergia richardsonis"
10	"Ligule generally < 1 mm; inflorescence axis generally visible between branches"	"Muhlenbergia utilis"
11	"Blade < 4 cm; lemma generally < 2 mm; stem generally < 3 dm"	"Muhlenbergia filiformis"
11	"Blade >= 5 cm; lemma generally > 2.5 mm; stem 2--15 dm"	12
12	"Inflorescence <= 15 cm, 1.5--4 cm wide; branches loosely flowered"	"Muhlenbergia jonesii"
12	"Inflorescence 15--60 cm, <= 1.2 cm wide; branches densely flowered"	"Muhlenbergia rigens"
13	"Inflorescence open, 6--15 cm wide, branches spreading"	"Muhlenbergia porteri"
13	"Inflorescence generally < 6 cm wide, branches ascending to appressed, occasionally spreading"	14
14	"Glumes 1 or 2, generally < 0.5 mm, vein 0"	"Muhlenbergia schreberi"
14	"Glumes 2, generally > 0.5 mm, vein(s) evident"	15
15	"Rhizome generally scaly, creeping"	16
15	"Rhizomes 0"	20
16	"Blade generally rolled, < 2 mm wide; anther purple, 1.5--3 mm"	17
16	"Blade generally flat, >= 2 mm wide; anther yellow, generally <= 1.5 mm"	18
17	"Lemma, palea short-soft-hairy on lower 1/2; stems loosely clumped, decumbent"	"Muhlenbergia arsenei"
17	"Lemma base sparsely short-hairy; palea glabrous to +- scabrous; stems erect, +- rooting at lower nodes"	"Muhlenbergia pauciflora"
18	"Hairs at lemma base 2--3.5 mm"	"Muhlenbergia andina"
18	"Hairs at lemma base < 1.5 mm"	19
19	"Lemma awn generally < 2.2 mm; anther 1--1.5 mm"	"Muhlenbergia californica"
19	"Lemma awn 2.5--9 mm; anther < 0.5 mm"	"Muhlenbergia mexicana"
20	"Upper glume 3-veined, 3-toothed"	"Muhlenbergia montana"
20	"Upper glume generally 1-veined, obtuse, acute, or awned"	21
21	"Lower glume 2-veined, 2-awned; inflorescence 5--8 mm wide, spike-like, dense"	"Muhlenbergia alopecuroides"
21	"Lower glume 1-veined, with 1 awn or awnless; inflorescence 5--30 mm wide, dense to loose"	22
22	"Glumes 0.5--1 mm, obtuse; cleistogamous spikelets generally present in lowermost stem axils"	"Muhlenbergia microsperma"
22	"Glumes generally 1.5--3.5 mm, acute, acuminate, or awned; cleistogamous spikelets 0"	23
23	"Lemma, palea short-soft-hairy on lower 1/2; stems loosely clumped, decumbent"	"Muhlenbergia arsenei"
23	"Lemma base sparsely short-hairy; palea glabrous to +- scabrous; stems erect, +- rooting at lower nodes"	"Muhlenbergia pauciflora"