Asclepias cordifolia |
Asclepias lemmonii |
|
---|---|---|
heart-leaf milkweed, purple milkweed |
big-leaf milkweed, Lemmon's milkweed |
|
Habit | Herbs. | Herbs. |
Stems | 1–20, ascending to spreading, unbranched, 25–100 cm, glabrous, glaucous, rhizomes absent. |
1–3, erect to ascending, unbranched, very stout, 100–150 cm, densely hirsute, not glaucous, rhizomes absent(?). |
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, petiolate, with 1 stipular colleter on each side of petiole; petiole 1–5 mm, hirsute; blade oval or oblong to ovate, 7–22 × 3–14 cm, subsucculent, base truncate to subcordate, margins entire, apex obtuse to truncate or emarginate, mucronate, venation brochidodromous, secondary veins nearly orthogonal, surfaces hirsute, margins ciliate, 8–16 laminar colleters. |
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. |
terminal, paired, and extra-axillary, pedunculate, 21–53-flowered; peduncle 6–13 cm, densely hirsute, with 1 caducous bract at the base of each pedicel. |
Pedicels | 16–37 mm, sparsely pilose. |
13–22 mm, densely hirsute. |
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 to pendent; calyx lobes lanceolate, 3.5–6 mm, apex acute, hirsute; corolla cream to greenish cream or ochroleucous, sometimes tinged pink, lobes reflexed with spreading tips, elliptic, 9–11 mm, apex acute, glabrous; gynostegial column 0.5–1 mm; fused anthers greenish brown, cylindric, 2.5–3 mm, wings right-triangular, closed, apical appendages oval; corona segments cream to ochroleucous, sometimes tinged pink, shiny, subsessile, conduplicate, 6–8 mm, equaling or exceeding style apex, apex truncate, spreading and tapering, glabrous, internal appendage laterally compressed, erect, barely exserted, glabrous; style apex shallowly depressed, green or pink. |
Seeds | ovate, 8–9 × 5–7 mm, margin not winged, faces reticulate-rugulose; coma 3–3.5 cm. |
ovate, 6–7 × 4–5 mm, margin winged, faces minutely rugulose; coma 4–4.5 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, lance-ovoid, 9.5–13.5 × 2–3 cm, apex attenuate, smooth, densely hirsute. |
2n | = 22. |
|
Asclepias cordifolia |
Asclepias lemmonii |
|
Phenology | Flowering Mar–Jul(–Aug); fruiting Jun–Sep. | Flowering Jun–Sep; fruiting Aug–Oct. |
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. | Canyons, slopes, streamsides, rocky and clay soils, pine-oak, pine, and riparian forests, oak woodlands, marshes. |
Elevation | 50–2200(–2800) m. [160–7200(–9200) ft.] | 1200–2200 m. [3900–7200 ft.] |
Distribution |
CA; NV; OR
|
AZ; Mexico (Chihuahua, Durango, Jalisco, Sonora, Zacatecas)
|
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.) |
A highly distinctive species, Asclepias lemmonii just barely enters the United States in southern Arizona (Cochise, Pima, and Santa Cruz counties), where it inhabits canyons in pine-oak clad sky-island ranges. Asclepias elata is a common co-inhabitant of these canyons. Asclepias lemmonii has been documented from the Baboquiviri, Chiricahua, Huachuca, and Santa Rita mountains, and it is not common in any of these. It is considered to be of conservation concern in Arizona. The large, hirsute leaves with nearly orthogonal venation and robust, hirsute stems of A. lemmonii are unmatched among American milkweeds. Plants may reach heights over 2 m in the main range of the species in the northern Sierra Madre Occidental. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 14. | FNA vol. 14. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Acerates cordifolia, Gomphocarpus cordifolius | |
Name authority | (Bentham) Jepson: Fl. W. Calif., 384. (1901) | A. Gray: Proc. Amer. Acad. Arts 19: 85. (1883) — (as lemmoni) |
Web links |