×leydeum

Barkworth
Treatment appears in FNA Volume 24. Treatment on page 369.
 TaxonIllustrator 
FNA24 P149 xLeydeum pg 371.jpeg×leydeum piperi
×leydeum dutillyanum
×leydeum littorale
Cindy Roché
Annaliese Miller
Cindy Roché
Annaliese Miller
Cindy Roché
Annaliese Miller

Plants perennial; rhizomatous, sometimes shortly so. Culms to 140 cm tall, 1-3 mm thick. Spikes 10-15 cm long, 5-12 mm wide excluding the awns, erect, sometimes lax, nodes with 2-3 spikelets; internodes 3-5 mm; disarticulation in the rachises, sometimes delayed. Spikelets appressed, with 1-3 florets. Glumes equal or unequal, 10-25 mm long, 0.2-1.5 mm wide, tapering from below midlength or subulate from the base; lemmas glabrous or hairy, awned, awns 1-10 mm; anthers 1.8-3 mm long, 0.1-0.3 mm thick. Caryopses not developed.

Discussion

×Leydeum consists of hybrids between Hordeum and Leymus. The number of named ×Leydeum hybrids is substantially lower than that for hybrids between Hordeum and Elymus.

This probably reflects the lower likelihood of such hybrids being formed, because Leymus does not incorporate the H genome of Hordeum, whereas Elymus does. It is also possible that such hybrids are less likely to be recognized, because inland species of Leymus, like Hordeum, have narrow glumes. Of the three species recognized, two involve the coastal species L. mollis, which has flat glumes; these hybrids have intermediate glumes and rachises that tend to disarticulate. ×Leydeum piperi, the only hybrid involving one of the inland species of Leymus, differs from Leymus in its disarticulating rachises, and from Hordeum in having 2 spikelets per node and 2-3 florets in the larger spikelets.

"decumbent" is not a number.

... more about "×leydeum"
membranous +  and scarious +
0.18 cm1.8 mm <br />0.0018 m <br /> (?) +  and 0.3 cm3 mm <br />0.003 m <br /> (?) +
toothed +, lobed +  and entire +
Mary E. Barkworth +
Barkworth +
1 (?) +  and 3 (?) +
basal +  and apical +
0.1 cm1 mm <br />0.001 m <br /> (1 cm10 mm <br />0.01 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
subulate +
swelling +
not evident +
cross +, linear +  and narrowly lanceolate +
spikelike +
hairy +  and glabrous +
not branching +
0 cm0 mm <br />0 m <br /> (140 cm1,400 mm <br />1.4 m <br />) +
not woody +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
1 +  and 3 +
laterally compressed +  and terete +
shorter than to longer than the adjacent florets +
10mm +  and 25mm +
subtending +
tapering +
unequal +
0.2mm +  and 1.5mm +
uncinate +
solid +  and hollow +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
hairy +  and glabrous +
keeled +, lanceolate +  and rectangular +
stiffly membranous +  and coriaceous +
inconspicuous +
lanceolate +
fleshy +  and membranous +
concealed +  and prominent +
2 +  and 1 +
hairy +  and glabrous +
well-developed +
slightly longer +
subequal +
dry +  and fleshy +
spikelike +
bowden1967c +, covas1949a +, hodgson1965a +  and hulten1968b +
10 cm100 mm <br />0.1 m <br /> (?) +  and 15 cm150 mm <br />0.15 m <br /> (?) +
subsessile +  and sessile +
bisexual +  and sterile +
terete +  and compressed +
1 +  and 3 +
simple +  and compound +
2 (?) +  and 3 (?) +
not papillate +
Gramineae +
×leydeum +
Poaceae tribe Triticeae +
membranous +
inconspicuous +
aquatic +  and terrestrial +