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Species Spotlight

Monsoon Peas and Beans

By Doug Moore

Abundant rains of the summer monsoon stimulate a great variety of flowering plants in Madera Canyon. Particularly interesting are the many annual vines that flourish with good precipitation and, covering and climbing the understory vegetation beneath the trees, give the canyon a “semi-tropical” appearance. It can be fun plant-detective work figuring out the different types.

Around Proctor, often the most prolific vines are the 4 or 5 species of morning glories (Ipomoea) that give up their showy blossoms briefly to the morning light. The oval leaves of Moonseed Vine, Cocculus diversifolia, also drape the foliage year-round under the mesquites on lower Proctor. But from the mesquite bosque at the Proctor Road up into the canyon in the dappled sunlight under the trees along creek drainages, a variety of flowering vines in the pea family are often the dominant vegetation covering ground and shrub.

These wild pea and bean vines are often slight with fairly typically-shaped bright pink pea flowers and leaves grouped in three leaflets (“leaves-in-threes”). Their seeds are held in pea pods. By looking closely at the structure of the blooms, the shape and size of the leaflets and where the plant is growing in the canyon, the different species can be relatively easy and fun to identify. Joan Lewis’ “Madera Canyon Wildflowers” is a great reference for helping to distinguish the different types from each other and Poison Ivy (another common canyon plant with “leaves-in –threes”).

Bushy Tick Clover, Desmodium batocaulon, is found along all canyon trails and may be the most common of these monsoon vines. It has light pink flowers sprouting little “elephants trunks” and oval leaflets with a whitish central splotch running up the central veins. Around Proctor, Tepary Bean, Phaseolus acutifolius, is also quite common, with a typical pink pea flower and long, lobed leaflets that resemble bird’s wings. Further up the canyon it is replaced by the similar Slimleaf Bean, Phaseolus angustissimus, with much narrower, lobed leaflets.

The largest and most distinctive flower of all the canyon peas is the beautiful Butterfly Pea, Clitoria mariana, each sporting a delicate, oval lavender banner petal up to 2” long. Butterfly Pea is found from White House Picnic Area up to Amphitheater. From around Amphitheater up the Bog Spring and Carrie Nation trails, Spotted Bean, Phaseolus maculates ssp. ritensis sends out distinctive long shoots of ten feet and more. These long stems are covered in large, deep green “triangular” leaflets and two foot-long upright flowers stalks. Spotted Bean seeds are indeed a handsome mahogany brown with dark spots. The tiniest flowers, only 1/8”, are grown by Rose’s Ticktrefoil, Desmodium rosei. The showiest and most colorful may be the brilliant red-purple flowers clustered on the two to three foot stalks of Spiked Ticktrefoil, Desmodium cinerascens, which can line the Bog Spring, Super and lower Four Springs trails.

There are but a few of the canyon’s monsoon peas and beans. Others to look for are Narrowleaf Tick Clover, Cologania angustifolia, with red-purple flowers; Gray’s Bean, Phaseolus grayanus, with pink blooms and ivy-like leaflets; and Graham’s Tick Clover, Desmodium grahami, with pink flowers and almost round, oval leaflets.

A September/October walk in Madera Canyon can be a monsoon flower extravaganza. Please take some time to look through the blossoms and see if you can find the wild peas and beans.

Bushy Tick Clover - Doug Moore Photo

Slimleaf Bean - Doug Moore Photo

Butterfly Pea
- Doug Moore Photo