Poa macrantha
Poa rhizomata
dune bluegrass, large flower sand dune blue grass, sand-dune blue grass, seashore blue grass
rhizome bluegrass, timber blue grass
(7)15-60 cm tall, 1.5-2 mm thick, bases decumbent, terete or weakly compressed, smooth or moderately scabrous below the panicles;
nodes terete, 0(1) exserted.
20-65 cm, erect or the bases decumbent, not branching above the base, terete or weakly compressed;
nodes terete, 1-2 exserted.
closed for about 1/2 their length, terete, glabrous or sparsely retrorsely scabrous, bases of basal sheaths glabrous, distal sheath lengths 1.7-4(6) times blade lengths;
collars smooth, glabrous;
ligules 1-5 mm, scabrous, truncate to acute, ciliolate;
innovation blades to 30 cm, moderately to densely scabrous or hispidulous on and between the veins;
cauline blades subequal in length, 2-4 mm wide, involute, thick, somewhat arcuate, firm, abaxial surfaces smooth or moderately to densely scabrous or hispidulous on and between the veins, apices narrowly prow-shaped, flag leaf blades 1-10 cm.
closed for 1/2-1/3 their length, slightly compressed, keels moderately distinct, smooth or sparsely to moderately scabrous, glabrous, bases of basal sheaths glabrous, distal sheath lengths 1.5-4.4(5.7) times blade lengths;
collars smooth, glabrous;
ligules of cauline leaves 2-8 mm, smooth or scabrous, acute to acuminate, innovation ligules 2-5 mm;
innovation blades to 20 cm, otherwise similar to the cauline blades;
cauline blades gradually reduced in length distally, 1-3.5 mm wide, usually flat or folded, soft, thin, somewhat lax, smooth or sparsely scabrous, primarily over the veins and margins, distinctly keeled, apices narrowly to broadly prow-shaped, flag leaf blades (1.4)3-6(8) cm.
mostly intravaginal, some extravaginal.
all or mainly extra vaginal.
3-15 cm, erect, ovoid to lanceolate, contracted, often interrupted, congested, with 15-80 spikelets, rachises glabrous, smooth to moderately scabrous;
nodes with 1-2 branches;
branches 1-6 cm, erect, stiff, terete to weakly angled, smooth or sparsely to moderately scabrous, with 3-17 spikelets.
(2)4-10 cm, nodding, ovoid, sparse, with 20-50 spikelets, proximal internodes usually 1.8-3 cm;
nodes with 1-2(4) branches;
branches 1.5-4.5 cm, ascending to spreading, lax, terete to weakly angled, angles sparsely to moderately scabrous, with 2-7 spikelets.
9-17 mm, lengths to 3 times widths, laterally compressed, not sexually dimorphic;
florets 3-6(10);
rachilla internodes smooth, usually hairy, hairs 0.3-0.4+ mm, rarely glabrous.
(4)6-9(12) mm, lengths to 3.5 times widths, laterally compressed, not sexually dimorphic;
florets 3-8, usually unisexual;
rachilla internodes smooth or sparsely scabrous, usually glabrous, infrequently sparsely puberulent.
broadly lanceolate, subequal to the adjacent lemmas, distinctly keeled, keels sparsely scabrous near the apices;
lower glumes 3-veined;
upper glumes usually 7+ mm, 3-5-veined;
calluses usually with a crown of hairs, sometimes glabrous or diffusely webbed;
lemmas (6)7.5-11 mm, lanceolate, 5-7(11)-veined, distinctly keeled, keels and marginal veins, and sometimes the lateral veins, short-villous to softly puberulent, intercostal regions smooth or scabrous, glabrous or softly puberulent, margins glabrous, apices acute;
palea keels scabrous, intercostal regions glabrous;
anthers vestigial (0.1-0.2 mm) or (2)3-4(5) mm.
3/5 – 4/5 as long as the adjacent lemmas, narrowly lanceolate to lanceolate, distinctly keeled, keels scabrous;
lower glumes 1-3(5)-veined;
calluses webbed, hairs over 1/2 the lemma length;
lemmas 4-6.5 mm, lanceolate, 5-7-veined, distinctly keeled, keels and marginal veins sparsely short- to long-villous, lateral veins moderately prominent, intercostal regions sparsely scabrous, glabrous, margins glabrous, apices acute;
palea keels scabrous;
anthers vestigial (0.1-0.2 mm) or 2.5-4 mm.
= 28.
=28.
Poa macrantha
Poa rhizomata
Poa macrantha is a dioecious coastal sand dune species that grows from southern Alaska to northern California. It competes better than P. douglasii (see previous) with the invasion of its habitat by Ammophila and other exotic species. It used to be treated as a subspecies of P. douglasii; a few intermediates with that species have been found around the mouth of Little River, California. Although clearly related, the two species are reasonably divergent in a number of characters. Poa macrantha is readily distinguished from P. douglasii by its glabrous rachises and usually longer glumes and lemmas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Poa rhizomata is a rare species that grows in upper elevation, mixed coniferous forests on ultramafic (gabro or peridotite) rocks of the Klamath-Siskiyou region. It is subdioecious.
Poa rhizomata resembles P. pratensis (p. 522), differing in having acute ligules, sparse inflorescences, florets that are usually unisexual florets, and generally larger spikelets. It also resembles P. chambersii (see next), but has more open sheaths, longer ligules, more pubescent lemmas, and a more well-developed web. It used to include P. piperi (p. 554), which differs in having involute, adaxially hairy leaves and glabrous lemmas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
