Asclepias speciosa
Asclepias macrosperma
asclépiade belle, showy milkweed
dwarf milkweed, large-seed milkweed, large-seed or dwarf or Eastwood's milkweed
1–few, erect, unbranched (rarely branched), 30–125 cm, tomentose to puberulent with curved trichomes, not glaucous, rhizomatous.
1–12, decumbent, unbranched or branched near base, 6–15 cm, densely puberulent with curved trichomes, not glaucous, rhizomatous.
opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole, sometimes also in axil;
petiole 4–12 mm, tomentose to pilose;
blade lanceolate or ovate to oblong, 6–20 × 2–14 cm, chartaceous, base rounded to truncate or cordate, margins entire, apex acute to obtuse, sometimes mucronate, venation faintly brochidodromous, surfaces tomentose to pilose, margins ciliate, 6–32 laminar colleters.
opposite or subopposite to alternate, petiolate, with 1 stipular colleter on either side of petiole;
petiole 1–5 mm, densely puberulent with curved trichomes;
blade lanceolate to linear-lanceolate or lance-ovate, 2.5–7 × 0.5–2 cm, chartaceous, base cuneate to truncate, margins crisped, apex attenuate, mucronate, venation obscure to faintly eucamptodromous, surfaces sparsely pilosulous to glabrate, midvein puberulent with curved trichomes to pilosulous, margins densely ciliate, laminar colleters absent.
extra-axillary, pedunculate, 3–34-flowered;
peduncle 1–10 cm, densely tomentose, with 1 caducous bract at the base of each pedicel.
terminal, sessile, 12–40-flowered, bracts few.
13–30 mm, densely tomentose.
9–19 mm, densely pilose.
erect to pendent;
calyx lobes elliptic, 4–8 mm, apex acute, tomentose;
corolla dark pink (rarely pale), lobes reflexed with spreading tips, elliptic, 9–12 mm, apex acute, densely pilose abaxially, hirtellous at base adaxially;
gynostegial column 0.5–1 mm;
fused anthers green and brown, truncately obconic, 2.5–3 mm, wings right-triangular, open, widely so at base, apical appendages deltoid;
corona segments pale pink to nearly cream, sessile, scoop-shaped, 9–15 mm, exceeding style apex, apex truncate with proximal tooth on each side and long-attenuate, flared, glabrous, internal appendage subulate, exserted, sharply inflexed over style apex, glabrous;
style apex shallowly depressed, green to cream or pink.
erect to pendent;
calyx lobes elliptic, 2.5–3 mm, apex acute, pilose;
corolla green, tinged red (especially abaxially), lobes reflexed, oval, 4–5.5 mm, apex acute, glabrous;
gynostegial column 0.2–0.8 mm;
fused anthers brown, cylindric, 1–1.5 mm, wings right-triangular, slightly open at tip, apical appendages ovate;
corona segments yellow to ochroleucous, subsessile, tubular, 2–3 mm, equaling or slightly exceeding style apex, apex truncate, glabrous, internal appendage falcate, exserted, sharply inflexed towards or over style apex, glabrous;
style apex shallowly depressed, green or pink.
ovate, 7–9 × 4–5 mm, margin winged, faces rugulose;
coma 2.5–3 cm.
ovate, 8–12 × 6–8 mm, margin thickly winged, faces densely rugulose;
coma 1.5–2 cm.
erect on upcurved pedicels, lance-ovoid, (5–)9–12 × 2–3 cm, apex long-attenuate, muricate or smooth, densely tomentose.
erect on upcurved pedicels, ovoid, 5–6.5 × 1.2–2 cm, apex acuminate, rugose, faintly striate, densely pilosulous.
= 22.
Asclepias speciosa
Asclepias macrosperma
Asclepias speciosa is the western counterpart of A. syriaca; both are broad-leaved species with large umbels of pinkish flowers. The distinctive, large, tapering corona segments, which form the broadest corona span of any American species of Asclepias, immediately distinguish A. speciosa from A. syriaca. These species hybridize extensively from Minnesota and southern Manitoba to Kansas, blurring the distinctions in the zone of contact, which corresponds roughly to the transition from tallgrass to mixed-grass prairie (R. P. Adams et al. 1987b). Not every individual in this zone can be readily assigned to one species or the other. This is the most extensive hybrid zone in North American Asclepias. These hybrids have also been documented in Illinois, far to the east of the contact zone. Possible hybrids with A. eriocarpa and A. hallii in California are discussed under those species. Outside of its contiguous range in the West, A. speciosa is known from a few sporadic, mostly historical records from Illinois, Michigan, Missouri, and Wisconsin. Most, if not all, of these records represent adventive, ephemeral outposts from the native range.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias macrosperma has not been consistently recognized as distinct from A. involucrata, as discussed under that species. It is quite homogeneous across its range on the Colorado Plateau, and intermediates with A. involucrata only occur where the ranges contact on the southern and eastern margins of the Plateau. It is readily distinguished from typical A. involucrata by broader leaves with crisped margins and smaller corona segments that are less compressed, less flared apically, and nearly uniformly yellow, as opposed to cream with a dark dorsal stripe. Also, A. macrosperma is largely confined to sandy, often unstabilized substrates, whereas A. involucrata occurs on stable, rocky, clay to sandy soils across most of its range. Asclepias macrosperma has been documented at few sites in Colorado (Montezuma County) and New Mexico (San Juan County) and should be considered to be of conservation concern in these states. It appears secure in Utah and on Navajo lands in Arizona.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
IL Wildflowers, 
KS Wildflowers, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, 
SW CO Wildflowers, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
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