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Vascular Plants of California
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Asclepias latifolia

Higher Taxonomy
Family: ApocynaceaeView DescriptionDichotomous Key
Habit: Annual, perennial herb, shrub, tree, often vine; sap generally milky. Leaf: simple, alternate, opposite, subwhorled to whorled, entire; stipules 0 or small, finger-like. Inflorescence: axillary or terminal, cyme, generally umbel- or raceme-like, or flowers 1--2. Flower: bisexual, radial; perianth parts, especially petals, overlapped, twisted to right or left, at least in bud; sepals generally 5, fused at base, often reflexed, persistent; petals generally 5, fused in basal +- 1/2; stamens generally 5, attached to corolla tube or throat, alternate lobes, free or fused to form filament column and anther head, filament column then generally with 5 free or fused, +- elaborate appendages abaxially, pollen +- free or removed in pairs of pollinia; nectaries 0 or near ovaries, then 2 or 5[10], or in stigmatic chambers; ovaries 2, superior or +- so, free [fused]; style tips, stigmas generally fused into massive pistil head. Fruit: 1--2 follicles, (capsule), [berry, drupe]. Seed: many, often with tuft of hairs at 1 or both ends.
Genera In Family: 200--450 genera, 3000--5000 species: all continents, especially tropics, subtropical South America, southern Africa; many ornamental (including Asclepias, Hoya, Nerium, Plumeria, Stapelia); cardiac glycosides, produced by some members formerly treated in Asclepiadaceae, used as arrow poisons, in medicine to control heart function, and by various insects for defense. Note: Asclepiadaceae ("asclepiads"), although monophyletic, included in Apocynaceae because otherwise the latter is paraphyletic. Complexity of floral structure, variation in asclepiads arguably greatest among all angiosperms. Pattern of carpel fusion (carpels free in ovule-bearing region, fused above), present +- throughout Apocynaceae (in broad sense), nearly unknown in other angiosperms. Base chromosome number generally 11; abundance of latex, generally small size of chromosomes evidently have impeded cytological investigations.
eFlora Treatment Author: Thomas J. Rosatti, except as noted
Scientific Editor: Bruce G. Baldwin.
Genus: AsclepiasView DescriptionDichotomous Key

Common Name: MILKWEED
Habit: Annual, perennial herb, shrub. Stem: prostrate to erect. Leaf: generally opposite (alternate, whorled), each pair at right angles to those below, above, generally persistent; blade narrow-linear to ovate or cordate. Inflorescence: terminal or at generally upper nodes, umbel-like cyme. Flower: ring of tissue at base of corolla 0; filament column appendages (hoods) free, elevated above corolla base or not, each often with an elongate projection (horn) attached to inside, margins converging and meeting or nearly meeting adaxially but not fused; anthers fused into anther head around and fused to pistil head, pollen in pollinia; pistil head flat or conic on top; nectaries in stigmatic chambers. Fruit: erect (but generally on pendent pedicel) or pendent, lance-ovoid to ovoid, smooth or with tubercles.
Species In Genus: In narrow sense of genus, 100 species: North America, Central America, perhaps South America. Etymology: (Greek physician Aesculapius) Note: Fresh flowers generally better for determining relative positions of parts; hoods may have near anther head 2 +- sickle shaped lobes each that may +- resemble horns. A. linaria not outside cultivation in California, so deleted here; previous inclusion in TJM2 (2012) based on faulty locality data.
eFlora Treatment Author: Thomas J. Rosatti & Carol A. Hoffman
Unabridged Reference: Liede-Schumann & Meve 2006; Woodson 1954 Ann Missouri Bot Gard 41:1--211
Asclepias latifolia (Torr.) Raf.
Habit: Perennial herb, very hairy, less so in age. Stem: erect. Leaf: opposite; petiole short to 0; blade generally wide-elliptic (lanceolate, ovate), base tapered, obtuse, or cordate, tip obtuse to truncate or notched, generally mucronate. Inflorescence: peduncle [0--]1.5--2.7 cm. Flower: corolla reflexed to spreading, cream-green, purple-tinged abaxially or not; hoods +- elevated above corolla base, exceeded by to at +- same level as anther head, cream, purple-tinged or not; horns exserted, at +- same level as hoods, converging over anther head or not. Fruit: erect on +- reflexed pedicels. Seed: 7--8 mm. Chromosomes: 2n=22.
Ecology: Dry washes; Elevation: +- 150 m. Bioregional Distribution: NCoRI (Rumsey, Yolo Co., 1912, extirpated); Distribution Outside California: to South Dakota, Texas, Mexico. Flowering Time: May--Jun
Unabridged Note: Based on key in Woodson: UC449991 (Tracy I. Storer; Jun 29, 1912; Rumsey, Yolo Co.), identified on label doubtfully as Asclepias latifolia (Torr.) Raf., may belong instead to Asclepias eriocarpa Benth. (peduncles in Asclepias latifolia 0--1.5 cm, in Asclepias eriocarpa 1--10 cm; on specimen +- 2.5 cm, and flowers few and past their prime); the material in a photocopy of MO1170403 (R.W. Schery & E. Curtis; July 19, 1939, 30 miles west of Grant Park, county not indicated, but the only Grant Park in the Jepson Place Name Index is in southwestern Ventura Co., well within the range of Asclepias eriocarpa and Asclepias erosa, but quite far away from the one dot indicated in California for Asclepias latifolia by Woodson, which evidently is in Inyo Co., possibly representing a locality within 30 miles -- but to the east -- of the Grant Grove area of Kings Canyon National Park, known in 1939 as General Grant National Park or simply Grant Park), identified on label (handwritten on otherwise typed label) and on annotation by S.P. Lynch in 1984 as Asclepias latifolia, also may belong instead to Asclepias eriocarpa. Tim Lowrey (pers. comm.), who is familiar with the sp. in New Mexico, remembers as a child plants possibly belonging to Asclepias latifolia occurring on dry washes near his family home near Rumsey (collection locality for UC449991). Final resolution will not occur at least until after a visit to the Rumsey area, planned for Spring of 2009, but until then it seems most judicious to treat this taxon as extirpated in California.
Jepson eFlora Author: Thomas J. Rosatti & Carol A. Hoffman
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

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Citation for this treatment: Thomas J. Rosatti & Carol A. Hoffman 2013, Asclepias latifolia, in Jepson Flora Project (eds.) Jepson eFlora, Revision 1,, accessed on June 17, 2021.

Citation for the whole project: Jepson Flora Project (eds.) 2021, Jepson eFlora,, accessed on June 17, 2021.

No expert verified images found for Asclepias latifolia.

Geographic subdivisions for Asclepias latifolia:
NCoRI (Rumsey, Yolo Co., 1912, extirpated)
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map of distribution 1
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Data provided by the participants of the  Consortium of California Herbaria.
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All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).