Petrophytum caespitosum

(Nuttall) Rydberg

Mem. New York Bot. Gard. 1: 206. 1900.

Illustrated
Basionym: Spiraea caespitosa Nuttall in J. Torrey and A. Gray, Fl. N. Amer. 1: 418. 1840
Synonyms: Eriogynia caespitosa (Nuttall) S. Watson Luetkea caespitosa (Nuttall) Kuntze
Treatment appears in FNA Volume 9. Treatment on page 413. Mentioned on page 411, 412.

Shrubs, 1–10+ dm diam. Stems prostrate or decumbent, loosely intertwined, 1–4+ cm, and erect or ascending, tightly coalesced, 0.2–0.5 cm, internodes 0.1–1 cm. Leaves: blade spatulate, 0.4–1.8 × 0.2–0.4 cm, venation rarely visible except on long-shoot leaves, 1 (–3) -veined, apex acute, abaxial surface pilose to sericeous, rarely sparsely strigose on lamina and veins. Panicles widely branched to compact and racemose, [0.5–] 1–15 [–20] × 0.5–6 cm, sericeous; bracts subulate to narrowly obtrullate, 3–8 mm, pilose to sericeous. Pedicels 0.5–2.5 mm; bracteoles 1, extending from middle to well beyond apex of sepals. Flowers 3–6 mm diam.; hypanthium 1 mm, densely sericeous; sepals erect, ovatelanceolate, 1–1.5 mm, margins sericeous, abaxial surface sericeous to tomentose; petals narrowly oblanceolate, 1–2.5 mm, apex obtuse to slightly cleft or acute to acuminate; stamens 20, lengths 1.5–2 (–2.5) times petals (1.5–3 times sepals); carpels (3–) 5 (–6), adaxially connate. Follicles 2 mm. 2n = 18.

Distribution

V9 697-distribution-map.jpg

Ariz., Calif., Colo., Idaho, Mont., N.Mex., Nev., S.Dak., Tex., Utah, Wash., ne Mexico

Discussion

Subspecies 2 (2 in the flora).

Petrophytum caespitosum primarily inhabits arid rocky outcrops and talus slopes at high elevations in mountain ranges of the western United States and northeastern Mexico.

Selected References

None.

Key

1 Leaf blades 0.4–1.4 cm, abaxial surfaces pilose to sericeous; petal apices obtuse to slightly cleft. Petrophytum caespitosum subsp. caespitosum
1 Leaf blades 1–1.8 cm, abaxial surfaces sparsely strigose; petal apices acute to acuminate. Petrophytum caespitosum subsp. acuminatum

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

... more about "Petrophytum caespitosum"
sericeous +  and tomentose +
Richard Lis +
(Nuttall) Rydberg +
gray +, brown +  and dark-brown +
compound +  and simple +
opposite +  and alternate +
Spiraea caespitosa +
1(-3)-veined +
2.5 cm25 mm <br />0.025 m <br /> (3 cm30 mm <br />0.03 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
spatulate +
0.2 cm2 mm <br />0.002 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
0.2cm +  and 0.4cm +
pilose +  and sericeous +
subulate +  and narrowly obtrullate +
3mm +  and 8mm +
hirsute +  and pilose +
Ariz. +, Calif. +, Colo. +, Idaho +, Mont. +, N.Mex. +, Nev. +, S.Dak. +, Tex. +, Utah +, Wash. +  and ne Mexico +
not +  and aggregated +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
canescent +  and sericeous +
unisexual +  and bisexual +
2 cm20 mm <br />0.02 m <br /> (?) +
pilose +, glabrate +  and glabrous +
lanceoloid +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
coriaceous +
not +  and aggregated +
not +  and aggregated +
1 cm10 mm <br />0.01 m <br /> (?) +
crassinucellate +
0.1 cm1 mm <br />0.001 m <br /> (1 cm10 mm <br />0.01 m <br />) +
compound +  and simple +
marcescent +
persistent +
entire +  and crenulate +
inferior +  and superior +
biseriate +  and clustered +
collateral +  and apical +
3 +  and 2 +
branched to compact +  and branched +
15 cm150 mm <br />0.15 m <br /> (20 cm200 mm <br />0.2 m <br />) +
1cm +  and 15cm +
0.5 cm5 mm <br />0.005 m <br /> (6 cm60 mm <br />0.06 m <br />) +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
0 (?) +  and 4 (?) +
persistent +
free +  and distinct +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
adnate +, free +, connate +  and distinct +
Mem. New York Bot. Gard. +
not arillate +
list;count +
persistent +
free +  and distinct +
ovatelanceolate +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
Illustrated +
free +  and distinct +
1.5-2(-2.5) times petals +
branched +  and simple +
intertwined +
coalesced +
decumbent +  and prostrate +
ascending +  and erect +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
persistent +  and deciduous +
distinct +
basal +, lateral +, subterminal +  and terminal +
not elongate +
sericeous +, pilose +, canescent +, strigose +  and glabrate +
Eriogynia caespitosa +  and Luetkea caespitosa +
Petrophytum caespitosum +
Petrophytum +
species +
inconspicuous +
thickened +  and minute +