Flora of North America species comparison

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Asclepias cordifolia

Asclepias sperryi

heart-leaf milkweed, purple milkweed

sperry's milkweed
Habit Herbs. Subshrubs, densely cespitose.
Stems

1–20, ascending to spreading, unbranched, 25–100 cm, glabrous, glaucous, rhizomes absent.

few–numerous, erect to ascending, branched at base, 5–20 cm, minutely puberulent with curved trichomes to glabrate, not glaucous, rhizomatous.
Leaves

opposite, sessile, stipular colleters absent;

blade ovate to lanceolate, 3.5–11 × 1.8–8 cm, chartaceous, base cordate, clasping, margins entire, apex acute, mucronate, venation brochidodromous to eucamptodromous, surfaces glabrous, glaucous, margins minutely ciliate, laminar colleters absent.

opposite, sessile, with 1 stipular colleter on each side of leaf base;

blade filiform, 2–5 × 0.05–0.1 cm, membranous, base cuneate, margins revolute, apex acute, mucronate, venation obscure, surfaces glabrous, margins minutely ciliate at base, laminar colleters absent.
Inflorescences

terminal, branched, sometimes also extra-axillary at upper nodes, pedunculate, 5–20-flowered;

peduncle 0.3–6.5 cm, apically sparsely pilose to glabrate, with few bracts.

extra-axillary, sessile, 1–2-flowered, with 1 caducous bract at the base of each pedicel.
Pedicels

16–37 mm, sparsely pilose.

4–10 mm, minutely puberulent with curved trichomes in a line.
Flowers

erect to pendent;

calyx lobes elliptic to lanceolate, 3–5 mm, apex acute, pilose;

corolla red-violet, lobes reflexed with spreading tips, oval, 6–7 mm, apex acute, glabrous;

gynostegial column 1–1.5 mm;

fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, open at tip, apical appendages deltoid;

corona segments white, tinged pink to red-violet at base, sessile, tubular, 2–3 mm, exceeded by style apex, base saccate, apex truncate, oblique, glabrous, internal appendage absent;

style apex shallowly depressed, pink to red-violet.

erect;

calyx lobes ovate, 2–3 mm, apex acute, glabrous;

corolla pale greenish yellow tinged with purple, lobes spreading, ovate, 4–5 mm, apex acute, glabrous;

gynostegium sessile;

fused anthers brown, cylindric, 1.5–2 mm, wings deltoid, apical appendages broadly ovate;

corona segments pale greenish yellow to white (sometimes tinted purple), sessile, chute-shaped, sharply inflexed, 2–3 mm, equaling to exceeded by style apex, apex truncate, subcaudate, hirtellous, internal appendage an included crest, hirtellous;

style apex shallowly depressed, green.
Seeds

ovate, 8–9 × 5–7 mm, margin not winged, faces reticulate-rugulose;

coma 3–3.5 cm.

ovate, 5–6 × 3–4 mm, margin thickly winged, faces rugulose;

coma 2–2.5 cm.
Follicles

erect on upcurved pedicels, lance-ovoid, 7.5–10.5 × 1.5–1.8 cm, apex long-acuminate, smooth, glabrous, glaucous.

erect on upcurved pedicels, fusiform, 5–7 × 0.5–0.7 cm, apex attenuate, smooth, glabrous.
2n

= 22.

Asclepias cordifolia

Asclepias sperryi
Phenology Flowering Mar–Jul(–Aug); fruiting Jun–Sep. Flowering Apr–Sep; fruiting Aug–Sep.
Habitat Hill­sides, canyons, ridge tops, streamsides, seeps, basalt, serpentine, gabbro, granite, shale, limestone, talus slopes, gravel, alluvium, oak woodlands, mixed ever­green, douglas-fir, pine, pine-oak, and riparian forests, chaparral, timberline meadows, grasslands. Slopes, ridges, canyons, limestone, rocky soils, desert scrub and desert grasslands.
Elevation 50–2200(–2800) m. (200–7200(–9200) ft.) 1300–1800 m. (4300–5900 ft.)
Distribution
from FNA
CA; NV; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
TX; Mexico (Coahuila)
[BONAP county map]
Discussion

Fresh leaves and stems of Asclepias cordifolia are often slightly or strongly colored bluish, grayish, or purplish. This is one of the few American species of Asclepias with cavitate corona segments that lack adaxial appendages. Such species were segregated along with diverse African species in Gomphocarpus R. Brown, a polyphyletic segregate (M. Fishbein et al. 2011; D. Chuba et al. 2017). Asclepias cordifolia is a distinctive species unlike any other within its range. It is phylogenetically and geographically isolated, although not highly derived morphologically. In Nevada, A. cordifolia is restricted to the Sierra Nevada, in Carson City, Douglas, and Washoe counties. Its range extends to northern California and southwestern Oregon.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Asclepias sperryi is one of the least known milkweeds. It is exceedingly cryptic and easily mistaken for a small clump of grass, perhaps of Bouteloua; it is likely to be far more common than documented. However, very few observations or collections have been made in recent decades, and conservation assessment is warranted. Its range is restricted to limestone mountains of the Chihuahuan Desert in the Big Bend region of Texas, in Brewster and Pecos counties, and adjacent areas of Coahuila, entirely within the range of its sister species, A. macrotis. It is the only species of Asclepias that regularly produces a single flower per umbel.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 14. FNA vol. 14.
Parent taxa Apocynaceae > Asclepias Apocynaceae > Asclepias
Sibling taxa
A. albicans, A. amplexicaulis, A. angustifolia, A. arenaria, A. asperula, A. brachystephana, A. californica, A. cinerea, A. connivens, A. cryptoceras, A. curassavica, A. curtissii, A. cutleri, A. eastwoodiana, A. elata, A. emoryi, A. engelmanniana, A. eriocarpa, A. erosa, A. exaltata, A. fascicularis, A. feayi, A. hallii, A. hirtella, A. humistrata, A. hypoleuca, A. incarnata, A. involucrata, A. labriformis, A. lanceolata, A. lanuginosa, A. latifolia, A. lemmonii, A. linaria, A. linearis, A. longifolia, A. macrosperma, A. macrotis, A. meadii, A. michauxii, A. nummularia, A. nyctaginifolia, A. obovata, A. oenotheroides, A. ovalifolia, A. pedicellata, A. perennis, A. prostrata, A. pumila, A. purpurascens, A. quadrifolia, A. quinquedentata, A. rubra, A. rusbyi, A. ruthiae, A. sanjuanensis, A. scaposa, A. solanoana, A. speciosa, A. sperryi, A. stenophylla, A. subulata, A. subverticillata, A. sullivantii, A. syriaca, A. texana, A. tomentosa, A. tuberosa, A. uncialis, A. variegata, A. verticillata, A. vestita, A. viridiflora, A. viridis, A. viridula, A. welshii
A. albicans, A. amplexicaulis, A. angustifolia, A. arenaria, A. asperula, A. brachystephana, A. californica, A. cinerea, A. connivens, A. cordifolia, A. cryptoceras, A. curassavica, A. curtissii, A. cutleri, A. eastwoodiana, A. elata, A. emoryi, A. engelmanniana, A. eriocarpa, A. erosa, A. exaltata, A. fascicularis, A. feayi, A. hallii, A. hirtella, A. humistrata, A. hypoleuca, A. incarnata, A. involucrata, A. labriformis, A. lanceolata, A. lanuginosa, A. latifolia, A. lemmonii, A. linaria, A. linearis, A. longifolia, A. macrosperma, A. macrotis, A. meadii, A. michauxii, A. nummularia, A. nyctaginifolia, A. obovata, A. oenotheroides, A. ovalifolia, A. pedicellata, A. perennis, A. prostrata, A. pumila, A. purpurascens, A. quadrifolia, A. quinquedentata, A. rubra, A. rusbyi, A. ruthiae, A. sanjuanensis, A. scaposa, A. solanoana, A. speciosa, A. stenophylla, A. subulata, A. subverticillata, A. sullivantii, A. syriaca, A. texana, A. tomentosa, A. tuberosa, A. uncialis, A. variegata, A. verticillata, A. vestita, A. viridiflora, A. viridis, A. viridula, A. welshii
Synonyms Acerates cordifolia, Gomphocarpus cordifolius
Name authority (Bentham) Jepson: Fl. W. Calif., 384. (1901) Woodson: Ann. Missouri Bot. Gard. 28: 246, fig. 2. (1941)
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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