Asclepias fascicularis
Asclepias cinerea
Mexican whorled milkweed, narrow-leaf milkweed, narrow-leaf or Mexican or Mexican whorled milkweed
ashy milkweed, Carolina milkweed
few–numerous, erect, sparsely to moderately branched, 50–150 cm, glabrous, not glaucous, rhizomes absent.
1, erect, unbranched (rarely branched), 20–100 cm, minutely puberulent in a line with curved trichomes to glabrate, not glaucous, rhizomes absent.
3–5-whorled, sessile or petiolate, with 1–3 stipular colleters on each side of petiole on a ciliate interpetiolar ridge;
petiole 0–4 mm, margins puberulent with curved trichomes;
blade linear to linear-lanceolate or narrowly elliptic, often somewhat conduplicate, 4.5–13 × 0.2–1.8 cm, membranous, base cuneate, margins entire, apex acute or attenuate to obtuse, mucronate, venation obscure to faintly eucamptodromous, surfaces glabrous, margins eciliate, laminar colleters absent.
opposite, sessile, with 1 or 2 stipular colleters on each side of leaf base;
blade filiform, 2–9 × 0.1–0.15 cm, membranous, base cuneate, margins entire, apex acute, mucronate, venation obscure, surfaces glabrous, laminar colleters absent.
terminal and extra-axillary at upper nodes, sometimes branched, pedunculate, 10–37-flowered;
peduncle 0.4–5.5 cm, puberulent with curved trichomes in a line to glabrate, with 1 caducous bract at the base of each pedicel.
terminal, branched, and extra-axillary at upper nodes, pedunculate, 2–8-flowered;
peduncle 0.5–1.7 cm, puberulent with curved trichomes on 1 side, with 1 caducous bract at the base of each pedicel.
9–14 mm, puberulent with curved trichomes to pilosulous.
10–25 mm, minutely puberulent with curved trichomes on 1 side.
erect;
calyx lobes lanceolate, 1.5–2 mm, apex acute, puberulent with curved trichomes to pilosulous;
corolla pale to dark pink, rarely pale green with a pink tinge, lobes reflexed with spreading tips, oval, 3–5 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 1–1.5 mm;
fused anthers green, cylindric, 1.5–2 mm, wings narrowly right-triangular, closed, apical appendages deltoid;
corona segments cream, often tinged or striped pink, stipitate, cupulate, dorsally somewhat flattened, 1.5–2 mm, exceeded by style apex, apex obtuse, glabrous, internal appendage acicular, exserted, arching towards style apex, glabrous;
style apex shallowly depressed, cream.
spreading to pendent;
calyx lobes lanceolate, 1.5–2 mm, apex acute, glabrous;
corolla cream, tinged gray, pink, or purple, faintly striate, lobes reflexed with spreading tips, elliptic, 4–5 mm, apex acute to obtuse, glabrous;
gynostegial column 0–0.5 mm;
fused anthers green, cylindric, 1.5–2 mm, wings narrowly right-triangular, open, apical appendages deltate;
corona segments cream, tinged gray, pink, or purple, sessile, conduplicate, dorsally flattened, 2–3 mm, equaling style apex, apex truncate with a proximal tooth on each side, glabrous, internal appendage a laterally flattened, included crest, glabrous;
style apex shallowly depressed, white.
ovate, 6–7 × 4–5 mm, margin winged, faces minutely rugulose;
coma 2.5–3 cm.
ovate, 6–7 × 4–5 mm, margin thickly winged, faces sparsely papillose;
coma 2.5–3 cm.
erect on straight pedicels, fusiform, 6–9 × 0.5–1 cm, apex attenuate, smooth, glabrous.
erect on straight pedicels, fusiform, 8–12 × 0.3–0.7 cm, apex long-attenuate, smooth, glabrous.
= 22.
Asclepias fascicularis
Asclepias cinerea
Asclepias mexicana Decaisne was misapplied to A. fascicularis in the past; this is the legitimate name of a related species endemic to southern and eastern Mexico. The common name Mexican (whorled) milkweed stems from this past confusion. Compared to its close relatives A. angustifolia, A. linearis, A. pumila, A. subverticillata, and A. verticillata, the leaves of A. fascicularis are not particularly narrow (despite the implication of another common name). However, very narrow leaves are found in A. fascicularis when it is growing at relatively dry sites, especially at the eastern limit of its range in southeastern Idaho. Such specimens (for example, Mumford 272 [MO], Atwood 28495 [NY]) have been attributed in the past to A. subverticillata in error. Asclepias fascicularis is completely allopatric with its Incarnatae clade relatives (species 7–16). Like these species, it is easily cultivated, and its seeds are widely available. In Washington, the range of A. fascicularis is restricted largely to the valleys of the Columbia and Spokane rivers and in Idaho to the Snake and Weiser rivers.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Similarities between Asclepias cinerea and A. feayi are discussed under the latter species. Asclepias cinerea inhabits flatwoods mostly north of the range of A. feayi, co-occurring only in Clay County as far as is known. Asclepias cinerea is sympatric with another similar species, A. viridula, across northern Florida. That species tends to grow in wetter woods and meadows than A. cinerea. In flower, they are easily distinguished by the spreading to pendent flowers, ashy lavender corollas, and corona segments with included, crestlike appendages of A. cinerea (versus erect to spreading flowers, green to brownish corollas, and corona segments with exerted, falcate appendages of A. viridula). Asclepias cinerea barely enters southeastern Alabama (Covington, Geneva, and Houston counties), and the species is considered to be of conservation concern in that state. Emergence and flowering of this species appears to be stimulated by precipitation events and/or fire.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
WA
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
