Holodiscus microphyllus var. glabrescens

(Greenman) F. A. Ley

Bull. Torrey Bot. Club 70: 284. 1943.

Endemic
Basionym: Spiraea discolor var. glabrescens Greenman Erythea 7: 116. 1899
Synonyms: Holodiscus discolor var. glabrescens (Greenman) Jepson H. dumosus var. glabrescens (Greenman) C. L. Hitchcock H. glabrescens (Greenman) A. Heller
Treatment appears in FNA Volume 9. Treatment on page 421. Mentioned on page 420.

Short-shoot leaf surfaces: abaxial light green, veins, intercostal regions, and margins not obscured by hairs, glabrous or glabrate, sessile or stipitate-glandular, without granular deposits, adaxial sparsely glabrate or glabrous, sessile-glandular, sometimes margins and veins sparsely hairy. Inflorescences 2–10 × 1–7 cm. Pedicels 1–2 mm. Flowers: nectar disc glabrous; sepals glabrous or puberulent, sessile-glandular; petal base glabrous or abaxial midvein with a few long hairs.


Phenology: Flowering May–Sep.
Habitat: Rock outcrops, talus slopes, mountaintops in alpine and subalpine habitats
Elevation: 1000–3000 m

Distribution

V9 709-distribution-map.jpg

Calif., Idaho, Nev., Oreg., Utah.

Discussion

Specimens that belong to var. microphyllus are frequently misidentified as var. glabrescens when the vestiture is short and dense, such that the leaf surfaces appear to be light green or gray and insufficient magnification is used to see the trichomes. Careful examination is required and in some cases 10× magnification is insufficient due to the short, dense indumentum that occurs in some populations of var. microphyllus. Variety glabrescens is glabrous or glabrate with sessile or stipitate glands alone on the smooth green epidermis. The variety inhabits the northern Great Basin region, in areas that recently have been geologically active, or on mountains adjacent to this region that are currently or were recently tectonically active. Individual populations often comprise a small number of individuals that occupy a narrow ecologic zone on mountain peaks.

Selected References

None.

Lower Taxa

None.

"chartaceous" is not a number."dm" is not declared as a valid unit of measurement for this property.

white +  and whitish +
stipitate-glandular +, sericeous +, tomentose +  and villous or sericeous +
beige +  and gray +
stipitate-glandular +, hirsute +  and hispid +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
sessile-glandular +  and stipitate +
villous +, velutinous +, puberulent +, glabrate +, glabrous +  and short-hirsute +
villous +, sessile-glandular +  and glabrate +
acute;acuminate +
Richard Lis +
(Greenman) F. A. Ley +
light +  and dark gray or nearly black +
exfoliating +
compound +  and simple +
opposite +  and alternate +
cuneate +, decurrent +  and acute +
Spiraea discolor var. glabrescens +
1.5 cm15 mm <br />0.015 m <br /> (3 cm30 mm <br />0.03 m <br />) +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
obtrullate +, broadly obovate +  and more or less ovate +
1 cm10 mm <br />0.01 m <br /> (10 cm100 mm <br />0.1 m <br />) +
coriaceous +
1 cm10 mm <br />0.01 m <br /> (?) +  and 2 cm20 mm <br />0.02 m <br /> (?) +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
sessile-glandular +  and stipitate +
puberulent +  and tomentose +
hispid +  and hirsute +
0.13 cm1.3 mm <br />0.0013 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Calif. +, Idaho +, Nev. +, Oreg. +  and Utah. +
not +  and aggregated +
1000–3000 m +
exfoliating +
puberulent +  and tomentose +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
unisexual +  and bisexual +
dolabriform +  and flattened +
not +  and aggregated +
not +  and aggregated +
Rock outcrops, talus slopes, mountaintops in alpine and subalpine habitats +
sessile-glandular +  and stipitate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
patelliform +  and shallowly crateriform +
2 cm20 mm <br />0.02 m <br /> (?) +  and 10 cm100 mm <br />0.1 m <br /> (?) +
pendulous +  and erect +
1 cm10 mm <br />0.01 m <br /> (?) +  and 7 cm70 mm <br />0.07 m <br /> (?) +
crassinucellate +
compound +  and simple +
deciduous +
10 cm100 mm <br />0.1 m <br /> (20 cm200 mm <br />0.2 m <br />) +
round +  and angled +
2 cm20 mm <br />0.02 m <br /> (10 cm100 mm <br />0.1 m <br />) +
serrate +  and entire +
not obscured +
hairy +, glabrous +, glabrate +  and stipitate-glandular +
toothed +, unlobed +  and lobed +
inferior +  and superior +
biseriate +  and clustered +
collateral +  and apical +
tomentose +, villous +, puberulent +  and glabrate +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
dark red +, maroon +  and shiny +
0 (?) +  and 4 (?) +
free +  and distinct +
ovate;elliptic +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
Flowering May–Sep. +
adnate +, free +, connate +  and distinct +
Bull. Torrey Bot. Club +
not arillate +
persistent +
free +  and distinct +
erect +  and spreading or slightly reflexed +
puberulent +  and glabrous +
triangular +  and deltate +
0.13 cm1.3 mm <br />0.0013 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
pilose-tomentose +, canescent +, downy +, glabrate +  and glabrous +
pleated +, angled +  and long +
0.2 cm2 mm <br />0.002 m <br /> (3 cm30 mm <br />0.03 m <br />) +
free +  and distinct +
0.25 cm2.5 mm <br />0.0025 m <br /> (?) +  and 0.3 cm3 mm <br />0.003 m <br /> (?) +
branched +  and simple +
erect +  and arching +
1 +  and 10 +
persistent +  and deciduous +
distinct +
basal +, lateral +, subterminal +  and terminal +
not elongate +
Holodiscus discolor var. glabrescens +, H. dumosus var. glabrescens +  and H. glabrescens +
Holodiscus microphyllus var. glabrescens +
Holodiscus microphyllus +
variety +
inconspicuous +
thickened +  and minute +
5 cm50 mm <br />0.05 m <br /> (15 cm150 mm <br />0.15 m <br />) +
erect +  and spreading +