Asclepias subulata


Asclepias subulata, (Rush Milkweed)

General Description

Mature plants of this species are striking in appearance with many leafless stems rising from a single root crown with a density similar to that of horsetails. Small leaves are produced after periods of rainfall. With or without rainfall, these plants usually bear a few umbels and then pendulous, narrow pods.


Form/Growth

Distribution: AZ, CA, NV

Flower: Umbels stand erect with 10 +/- flowers per umbel located at top part of stem. Flower is glabrous, approximately ½ inch (1.5 cm) long by ¼ inch (.5 cm) wide. Corolla, hoods, and horns are cream, white, or yellow color.  Corolla folds back to expose hoods and horns.

Foliage: Leaves are indistinct (small) and tend to be maintained only when moisture is adequate. Photosynthesis appears to be accomplished via greenish-white tissues that cover numerous erect stems.  Leaf arrangement is opposite. Grows as numerous stems off a common root crown.  Color is a grayish green.

Habitat: Desert areas on dry slopes and plains.

Growth habit: Non-clonal, non-invasive. Slow to become established under natural conditions.

Height: 24 – 48 in (61-122 cm).

Leaves: Remains leafless until after rainfalls.  Leave shape is linear, 1-2 in (2 ½-5 cm) long by up to 1/8 in (3 cm) wide.

Roots: Taproot.

Toxicity: Low.


Reproductive

Blossoming Season: April – December.

Life span: NA.

Propagation: By seed.

Pods: Narrow, smooth, glabrous, downwardly directed and 2-4 in (5-10 cm) long when mature.

Seed Color: Brown.


Environment and Growth Requirements

Maintenance: Low.

Overhead Conditions: Shade tolerant under desert conditions.

Precipitation: Less than 8 in to 16 in (20-40 cm) annually.

Soil Texture: Sandy, rocky and dry.

Temperature: Can tolerate a minimum temperature of 10 to 20 Fahrenheit (-12 to -6 Celsius).




Work Cited: wildflower.org, Plants.usda.gov, Wikipedia.org, Davesgarden.com, Arborday.org, Eduplace.com, ag.arizona.edu

Photos: Gary Stell, Morris Family

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