Phaseolus maculatus is a prostrate and trailing perennial herb that is easy to recognize by virtue of the large size of the herbage. The leaves are trifoliate, with each leaflet round to oval and 40-80mm long. The leaflets point upwards rather than being positioned flat on the ground. The flowers are small in comparision, and purple when fresh. The pods are 5-7cm long and glabrous. Phaseolus maculatus is found exposed on dry, rocky hillsides at middle elevation.
Duration: Perennial
Nativity: Native
Lifeform: Vine
General: Prostrate, scandent or twining perennial with slender, striate, sparsely puberulent stems 2-10 dm long, onder ones often strongly zigzag; root woody, to 1.5 cm in diameter, stipules oblong-lanceolate to narrowly lanceolate .8-1.5 mm wide, 3-5 mm long, strongly striate, finely puberulent to subglabrate.
Leaves: Petioles 1-3 cm long, sparsely puberulent, leaflets ovate to broadly rhombic-ovate, symmetrical or nearly so, entire, 1.5-3.5 cm wide, 2-5.5 cm long, rather leathery, light green, subglabrate and finely reticulate-veined above, slightly paler, sparsely puberulent and conspicuously veined beneath, acute to obtuse and slightly emarginated at apex, rounded to broadly cuneate at base.
Flowers: Peduncles usually surpassing leaes, to 30 cm long, flowering racemes equaling or exceeding basal portion; pedicels slender, 3-5 mm long, and ascending at anthesis, to 1.5 cm long and reflexed in fruit; calyx broadly campanulate, 2-3 mm high, fully as wide, subglabrate, teeth broader than long, shorter than tube, corolla pale lavender, 6-9 mm long.
Fruits: Pods 4-7 mm wide, 3-4 cm long, more or less falcate, very abruptly turned upward at base, abruptly prostrate at apex, strongly flattened, glabrous.
Ecology: Found on valley floors and rocky hillsides, common to oak woodlands to down to upper margins of Sonoran Desert from 4,500-7,000 ft (1372-2134 m); flowers August-September.
Distribution: AZ, sw NM, s TX; south to c MEX.
Notes: Similar to other bean species by being a spreading vine with a flower containing a keel which curls back; distinguished by being a perennial with entire, rounded, egg-shaped leaflets with rounded to pointed tips, and rough hairs that make them feel like sandpaper, the leaflets lager and more rounded than most regional species; also distinctive are the broad, flattened, falcate pods. This species has been placed under multiple names. It has a odd, disjunct distribution in many habitats and may have been carried to those locations and planted by prehistoric Native Americans.
Ethnobotany: The seeds which are quick to fall from ripened pods are large and can be prepared like teparies.
Etymology: Phaseolus is from Greek phaselos, a little boat or light vessel, referring to its pod, while ritensis is a reference to the Santa Rita Mountains.
Synonyms: Phaseolus ritensis, Phaseolus metcalfei
Editor: SBuckley 2010, FSCoburn 2015
