Asclepias subulata Decne.
Family: Apocynaceae
Rush Milkweed,  more...
Asclepias subulata image

Plant: shrub, 80-300 cm tall; stems erect or ascending, wand-like, branching above, glabrous, more or less glaucous and grayish green, in age leafless; milky sap

Leaves: opposite, narrowly linear, 1-5 cm long, deciduous at about the time of early flowering

INFLORESCENCE: UMBELS lateral and sometimes approximate at the upper nodes, 3-6 cm broad, the peduncles mostly 0.5-3 cm long, glabrate, the pedicels more or less pubescent

Flowers: rather large; calyx lobes 2-4 mm long; corolla mostly greenish, the lobes 7-11 mm long; hoods yellowish, erect, oblong, dilated in the upper portion to a truncate or oblique apex, 5-9 mm long, 2-4 mm broad at the top, 2-5 mm longer than the gynostegium, the horns attached in the upper half of the hoods, radially flat, more or less triangular, with an inwardly pointed, beaklike tip, concealed within the hoods or scarcely exserted; anther wings 2.2-2.8 mm long; corpusculum 0.4-0.5 mm long, the pollinia 1.3-1.6 mm long

Fruit: FOLLICLES more or less pendulous on spreading to drooping peduncles and pedicels, 8-13 cm long

Misc: Desert washes and scrub communities; 50-850 m (200-2800 ft); all year

REFERENCES: Sundell, Eric. 1994. Asclepiadaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 169-187.

Sundell 1993, Woodson 1954, Benson and Darrow 1981, Wiggins 1964, Nabhan et al 2015

Duration: Perennial

Nativity: Native

Lifeform: Subshrub

General: Slender twiggy subshrub 0.8-3 m tall, stems erect or ascending in clusters, wand-like, branching above, glabrous, more or less glaucous and grayish green, in age they are leafless.

Leaves: Opposite, narrowly linear, 1-5 cm long, deciduous at about the time of early flowering.

Flowers: Umbels lateral and sometimes approximate at upper nodes, 3-6 cm broad, peduncles 0.5-3 cm long, glabrate, pedicels more or less pubescent; calyx lobes 2-4 mm long, corolla greenish, lobes 7-11 mm long; hoods yellowish, erect, oblong, dilated in upper portion to a truncate or oblique apex, 5-9 mm long, 2-4 mm broad at top; horns attached in upper half of hoods, radially flat, more or less triangular, inwardly pointed, beaklike tip, concealed within the hoods or scarcely exserted.

Fruits: Follicles more or less pendulous on spreading to drooping peduncles and pedicels, 8-13 cm long, spindle shaped and long acuminate at each end; seeds 5-6 mm long, coma 2.5-3 cm long.

Ecology: Found on sandy or gravelly plains, rocky slopes, or along washes from sea level to 3,000 ft (914 m); flowers sporadically year round.

Distribution: This is a Sonoran Desert endemic, stretching across the low desert portions of the Baja, Sonora, AZ, CA, and NV.

Notes: Largely a plant of the low desert, the narrow rushlike stems are characteristic of this plant. There is another similar species A. albicans which can be told apart by the stems being covered in a white wax and its habit of having many stems from the base as opposed to just a few and very tall compared to very short hoods. Woodson 1954 described this species as extremely uniform in terms of its floral structure. Average 88,560 seeds per pound. This is a known monarch host plant.

Ethnobotany: Used as a cathartic, an emetic, an eye medicine, for stomach disorders, for many other ailments, but it is also considered poisonous.

Etymology: Asclepias is named for the Greek god of healing Asklepios, subulata means awl-shaped.

Synonyms: None

Editor: SBuckley 2010, 2014, AHazelton 2015

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Dave Sussman  
Asclepias subulata image
Dave Sussman  
Asclepias subulata image