Key to Hordeum

View taxon page for Hordeum

(For a list of species in Hordeum, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Auricles of upper leaves well developed, 1–4(8) mm

2. Inflorescence axis generally remaining intact at maturity; lateral 

spikelets 

1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts.

 

sessile 

Without a petiole, peduncle, pedicel, or other kind of stalk.

(stalked in sterile plants); 

glume 

In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets.

 margins not 

ciliate 

Having generally straight, conspicuous hairs along margins or edges.

..... [H. vulgare]

2' Inflorescence axis breaking apart at maturity; lateral spikelets stalked; glume margins ciliate ..... H. murinum

3. Central 

spikelet 

1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts.

stalk 0–0.5 mm; 

lemma 

In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret.

of central floret generally = lemma of lateral floret; 

palea 

1. In Asteraceae, a scale-like bract that subtends an individual flower on the receptacle (equal to 'chaff scale' in TJM), absent in some genera, restricted to a ring separating ray and disk flowers in most tarweed species. 2. In Poaceae, the distal, generally smaller of two sheathing bracts subtending a flower, generally two-veined and -keeled and ensheathed by the lemma; with the lemma and flower, comprising the floret.

of lateral floret scabrous to glabrous ..... subsp. murinum

3' Central spikelet stalk 1–2 mm; lemma of central floret < lemma of lateral floret; palea of lateral floret hairy or scabrous on lower 1/2

4. Lemma of central floret <= those of lateral 

florets 

In Poaceae, a single flower and its immediately subtending bracts (lemma and generally palea, the lemma subtending the palea when the latter is present); in a sterile floret, the flower and sometimes palea are rudimentary or absent.

; palea of lateral florets long-hairy on lower 1/2; anthers of central florets < 1/2 those of lateral florets ..... subsp. glaucum

4' Lemma of central floret << those of lateral florets; palea of lateral florets scabrous on lower 1/2; anthers of central spikelets = those of lateral florets ..... subsp. leporinum

1' Auricles of upper leaves generally 0 (vestigial rudiments occasionally present on lower leaves)

5. Glumes strongly divergent at maturity

6. Glumes of central spikelet 11–28 mm, flat near base ..... H. arizonicum

6' Glumes of central spikelet (15)35–85 mm, bristle-like throughout ..... H. jubatum subsp. jubatum

5' Glumes generally straight with age (slightly 

spreading 

Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal.

in some Hordeum brachyantherum)

7. Perennial herb; inflorescence fully 

exserted 

Protruding out of surrounding structure(s) (e.g., stamens exserted from corolla).

at maturity ..... H. brachyantherum

8. Leaf 

sheath 

A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae.

generally glabrous, 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

glabrous or sparsely short-hairy; stem generally robust ..... subsp. brachyantherum

8' Leaf sheath generally densely hairy, blade generally short- and long-hairy; stem slender ..... subsp. californicum

7' Annual; inflorescence generally ± enclosed in upper sheath at maturity (except Hordeum marinum subsp. gussoneanum)

9. Awn of lateral spikelet lemma 3–8 mm ..... H. marinum subsp. gussoneanum

9' Awn of lateral spikelet lemma 0–1.2 mm

10. Nodes glabrous; glumes of central spikelet rounded to slightly flattened near base ..... H. depressum

10' Nodes generally pubescent; glumes of central spikelet distinctly flattened at base ..... H. intercedens

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