Flora of North America species comparison

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Oreostemma

aster, mountain-crown
Habit Perennials, 2–40(–70) cm (taproots, sometimes thickly rhizomatous, sometimes with branching caudices).
Stems

decumbent-ascending to erect, simple (essentially scapose), usually distally finely, loosely tomentose, sometimes stipitate-glandular.
Leaves

mostly basal (persistent rosettes), cauline reduced; alternate;

sessile;

blades 3-nerved, linear to oblanceolate, margins entire (apices acute to obtuse or rounded), faces glabrous, sparsely villous, or stipitate-glandular.
Involucres

broadly turbinate, (5–12 ×) 10–20 mm.
Receptacles

flat, shallowly pitted, epaleate.
Ray florets

10–40, pistillate, fertile;

corollas white, often drying blue to purple.
Disc florets

30–55, bisexual, fertile;

corollas yellowish at maturity, tubes shorter than tubular throats (barely constricted), lobes 5, erect, lanceolate to deltate;

style-branch appendages linear-lanceolate.
Phyllaries

25–40 in (2–)3–4 series, appressed (commonly purplish), 1(–3)-nerved (thin, not resinous; often low-keeled), linear to linear-elliptic or oblanceolate, subequal, usually herbaceous, sometimes proximal margins indurate, faces finely and loosely tomentose.
Heads

radiate, borne singly.
Cypselae

(brownish) narrowly cylindric, ribs 5–10 (raised), faces glabrous or sparsely strigillose;

pappi persistent, of 25–40, tawny-white, barbellate, apically attenuate bristles in 1 series, sometimes plus shorter bristles or setae in a second, outer series.
x

= 9.

Oreostemma
Distribution
from USDA
w United States
[BONAP county map]
Discussion

Species 3 (3 in the flora).

Oreostemma is distinguished by its basal rosettes of narrow, 3-nerved leaves, single heads on scapose stems, turbinate involucres with (2–)3–4 subequal series of herbaceous phyllaries, white rays, long style-branch appendages, and cylindric cypselae. The species mostly have been previously treated within Aster.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Plants 2–7 cm; stems, phyllaries, and often leaves sparsely villous to glabrate, densely short-stipitate-glandular; leaf blades linear
O. peirsonii
1. Plants 4–70 cm; stems, leaves, and phyllaries glabrous or villous, eglandular; leaf blades oblanceolate
→ 2
2. Stems, leaves, and phyllaries villous to glabrate, at least some hairs always perceptible on distal stems and proximal portions of phyllaries; phyllaries herbaceous or slightly tawny-indurate proximally, outer 0.8–1.2 mm wide proximally, 1-nerved
O. alpigenum
2. Stems, leaves, and phyllaries glabrous; phyllaries strongly indurate-stramineous proximally, outer 1.5–2 mm wide proximally, 3-nerved (nerves separating phyllary into 4 longitudinal bands)
O. elatum
Source FNA vol. 20, p. 359. Author: Guy L. Nesom.
Parent taxa Asteraceae > tribe Astereae
Subordinate taxa
O. alpigenum, O. elatum, O. peirsonii
Synonyms Oreastrum
Name authority Greene: Pittonia 4: 224. (1900)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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