Asclepias tuberosa
Asclepias feayi
asclépiade tubéreuse, butterfly milkweed
Feay's milkweed, Florida milkweed
1–numerous, erect to ascending, branched in inflorescence, 15–90 cm, densely hirsute, not glaucous, rhizomes absent.
solitary, erect, unbranched (rarely near base), 20–75 cm, minutely puberulent in a line with curved trichomes to glabrate, not glaucous, rhizomes absent.
alternate, petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 1–4 mm, densely hirsute;
blade elliptic, oblong, or oblanceolate to lanceolate or linear, 2–12 × 0.3–3 cm, chartaceous, base cuneate or obtuse to rounded, truncate, hastate, or cordate, margins entire, apex acute to attenuate or obtuse to rounded, venation brochidodromous to eucamptodromous, surfaces hirsute, more densely so on midvein abaxially, margins ciliate, 0–4 laminar colleters.
opposite, sessile, with 1 or 2 stipular colleters on each side of leaf base;
blade filiform, 2.5–10 × 0.1–0.15 cm, membranous, base cuneate, margins entire, apex acute, venation obscure, surfaces glabrous, laminar colleters absent.
corymbs of extra-axillary umbels on branches, sessile or pedunculate, 5–27-flowered;
peduncle 0–4 cm, sometimes branched, hirsute, with 1 caducous bract at the base of each pedicel.
terminal, sometimes branched, and often extra-axillary at upper nodes, sessile or pedunculate, 2–7-flowered;
peduncle 0–5 cm, puberulent with curved trichomes on 1 side, with 1 caducous bract at the base of each pedicel.
9–24 mm, puberulent with curved trichomes to pilosulous.
7–17 mm, minutely puberulent with curved trichomes on 1 side.
erect;
calyx lobes narrowly lanceolate, 2–3 mm, apex acute, hirsute to puberulent with curved trichomes;
corolla reddish orange (nearly red) to orange or yellow, lobes reflexed with spreading tips, narrowly elliptic, (5–)6–8 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 1.2–1.5 mm, fused anthers yellow to yellowish green, cylindric, 2–3 mm, wings right-triangular, closed, apical appendages ovate;
corona segments reddish orange (nearly red) to orange or yellow, substipitate, conduplicate, dorsally flattened, sulcate, 5.5–7 mm, greatly exceeding style apex, apex acute, glabrous, internal appendage subulate, exserted, arching above style apex, glabrous;
style apex shallowly depressed, yellow to yellowish green.
erect;
calyx lobes narrowly lanceolate, 1.5–2.5 mm, apex acute, glabrous;
corolla white, sometimes pale lavender-tinged, inconspicuously striate, lobes spreading, lanceolate, 7–10 mm, apex acute to obtuse, glabrous;
gynostegium sessile;
fused anthers lavender, cylindric, 1.5–3 mm, wings narrowly right-triangular, open at base, apical appendages ovate;
corona segments white, sessile with a basal collar, cupulate, 2.5–4 mm, equaling to slightly exceeding style apex, apex obtuse, glabrous, internal appendage a laterally flattened, included crest, glabrous;
style apex shallowly depressed, lavender.
ovate, 8–9 × 4–5 mm, margin winged, faces minutely rugulose;
coma 3–5 cm.
oval, 6–8 × 3–5 mm, margin winged, faces smooth;
coma 3.5 cm.
erect on upcurved pedicels, fusiform, 7–14 × 1.2–2 cm, apex long-acuminate or attenuate, smooth, hirsute.
erect on straight pedicels, fusiform, 9–12 × 0.3–0.6 cm, apex attenuate, smooth, glabrous.
= 22.
Asclepias tuberosa
Asclepias feayi
Subspecies 3 (3 in the flora).
Asclepias tuberosa is one of the most familiar and beloved North American milkweeds and is a favored element of pollinator gardens because of the cheery orange flowers that attract abundant insect visitors. The clear latex is unusual in the genus and is often commented upon by collectors. The subspecies of A. tuberosa are highly intergrading. It is often difficult to satisfactorily place a given specimen in a particular subspecies; however, the great majority are readily assigned. It appears that the conspicuous variation in leaf morphology across the subspecies corresponds to genetically structured population variation (R. E. Woodson Jr. 1947). However, it is unknown to what extent cultivation and other human activities have blurred the distinctions among the geographic variants. Future recognition of the subspecies should be supported by genetic study with modern techniques. Although yellow-flowered plants predominate in the western plains, color variation is often pronounced in single populations, and yellow flowers may be encountered anywhere in the range. Hybridization with A. syriaca is documented, but is exceedingly rare. Presumed hybrids can be recognized by intermediate floral and vegetative traits.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias feayi is one of a trio of very slender milkweeds in the southeastern United States, along with A. cinerea and A. viridula. These species are divergent in floral morphology, but without flowers they are very difficult to distinguish (even in fruit), and they appear to be close relatives. However, A. feayi occurs primarily in peninsular central and southwestern Florida, from Lake to Collier counties, most commonly in scrub. A single disjunct population has been documented from Clay County in the northeastern part of the state (Hall 1896 [FLAS]). Asclepias cinerea and A. viridula are found in northern Florida or further north, in flatwoods. All three species are cryptic in the absence of flowers and appear to respond positively to fire and rainfall events. They are likely to be more common than is apparent because they are inconspicuous and emerge episodically. Nonetheless, numerous historical locations for A. feayi have been developed and are no longer capable of supporting populations, and its conservation status merits evaluation. An unusual putative hybrid with A. pedicellata represented by a single collection is documented from Marion County (Judd 2639 [FLAS]), suggested by the exactly intermediate floral morphology.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf bases hastate, blade margins crisped. | subsp. rolfsii |
1. Leaf bases cuneate, obtuse, rounded, truncate, or subcordate, blade margins planar. | → 2 |
2. Leaf bases cuneate to obtuse, rounded, or subcordate, apices rounded to acute, mostly east of the crest of the Appalachian Mountains. | subsp. tuberosa |
2. Leaf bases truncate or obtuse to cordate, apices acute to attenuate, mostly west of the crest of the Appalachian Mountains. | subsp. interior |
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