Parkinsonia microphylla Torr.
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Authority
Isley, Duane. 1975. Leguminosae of the United States: II. Subfamily Caesalpinioideae. Mem. New York Bot. Gard. 25 (2): 1-228.
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Family
Caesalpiniaceae
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Scientific Name
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Description
Species Description - Tangle-branched, highly floriferous thorny shrub or spreading tree to 6 m of yellow or olive-green leafless aspect. Twigs and branches photosynthetic, initially puberulent, many short, determinate, and spine-tipped. Leaves 1-2 per node, 2-pinnate with 2 pinnae but subsessile and each pinna resembling a1-pinnate leaf; rachis l-2(-3) cm; leaflets (2-)3-5(-9) pairs, distant, sessile, ovate, 1-2 mm, 1.2-1.8 r, thick, without evident nervation, often deciduous in dry season. Flowers 4-8 in intercalary, congested, puberulent racemes, 2-3 cm from first and second year twigs and usually appearing before leaves. Pedicels 6-9 mm, continuous with 2 mm short-turbinate hypanthium; calyx 4-6 mm, divided ca 5/6 of length, lobes soon reflexed and deciduous leaving persistent basal cup; corolla yellow, 12-14 mm diam; petals subequal, clawed, standard whitish to creamy; filaments ca 10 mm, villous, anthers orange; pistil villous. Legume deciduous, tardily dehiscent, flat-stipitate from persistent calyx cup, torulose, compressed-turgid, 3-8 cm long, 6-8 mm wide, with a curved flat beak 1.5 cm; valves woody with 1-3 segments separated by sterile isthmi of varying lengths, brown, striate. Seeds 1-3.
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Discussion
Cercidium microphyllum (Torr.) Rose & I. Johnst. ex I. Johnst. (1924) Cercidiopsis microphylla (Torr.) Britt. & Rose (1930) CN 2n = 28 (Turner and Fearing, 1960; as Cercidium microphyllum). Of the two desert palo verdes, Parkinsonia florida is somewhat the showier of the two at anthesis, comes into flower first, and is found most characteristically at lower elevations in washes and on flats where subsurface moisture is available, P. microphylla being commoner on foothills slopes. During the summer, their branches contrast; P. microphylla, yellow-green, and P. florida, blue-green. Parkinsonia microphylla differs from other traditional Cercidium in its torulose pod, armature of spine-tipped twigs rather than intercalary thorns, and in elimination of the primary leafstalk which, however, as well as solitary nodal thorns is present in seedlings. In fruit and leaf features it resembles P. aculeata to which it is possibly most closely related. Benson and Darrow (1944) note that both P. microphylla and P. florida furnished the Indians with seeds for food and wood for fuel.
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Distribution
S Arizona to se California. Dry rocky desert slopes, mountain foothills, mesas, canyons, washes, often locally common with saguaro, ocotillo, et al. or sometimes locally dominant. 2500-4000 ft. April-May(-June). Palo Verde. Foothill Palo Verde. Mexico.
United States of America North America| Mexico North America|