Basic Literatur

THE TAXONOMY AND ETHNOBOTANY OF YUCCA MADRENSIS

JOSEPH E. LAFERRIERE

Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721

When Gentry (1972) described Yucca madrensis, a rare species endemic to the Sierra Madre Occidental of Northwest Mexico, he stated that it was impossible to ascertain the taxonomic relationships of this species with certainty until fruits had been collected. I have recently obtained fruits of the species and can confirm Gentry's speculation as to the plant's relationships, as well as adding to the ethnobotanical literature on the plant, based on my recent fieldwork among the Mountain Pima.

The description of Y. madrensis was based on flowering specimens collected in the Sierra Charuco of the Mexican state of Sonora and originally identified as Y. rigida Trel. (Gentry, 1942). This identification was based primarily on the serrate leaf margins shared by both taxa. Gentry (1972) later, however, decided to assign the specimens to a new taxon based on several characters which separated these specimens from Y. rigida, and seemed to suggest a relationship with Y. schottii Engelm., based on the short stature, inflorescence characters, and thin, flexuous leaves. It differed from Y. schottii, however, in its extremely small size (1-2 m), narrow leaves (2-3 cm in width), nonsurculose habit, glabrous filaments, and serrate, non-filiferous leaf margins. They also differ in that the flower stalk is only sparingly pubescent in Y. madrensis, densely so in Y. schottii. Despite the close resemblances, and some evidence of introgression noted by Gentry, the placement of the new species with Y. schottii was problematic. No other species of the section Sarcocarpa Engelm. in S. Wats., to which the latter belongs, contains no other known members with serrate leaf margins (Gentry, 1972).

I collected fruits of Y. madrensis from the vicinity of the Mountain Pima village of Nabogame, Chihuahua, 28°30'N, 108°30'W, elevation 1,800 m (Laferriere 2266, ARIZ, MEXU). The site is some 60 km north of the type locale of the species. In Nabogame, the plant is found primarily on shaded, north-facing slopes in pine/oak forest. It is becoming somewhat rare due to overutilization. The fruits (Fig. 1) are 7-13 cm long, fleshy, indehiscent, and bear irregular warts up to 2 cm in diameter. The seeds (Fig. 2) are 6-9 long x 6-10 mm broad, black, thick, rough, and flat or rounded depending on their relative location in the fruit. Both are very similar to those of Y. schottii. Some of the leaves did, contrary to Gentry's description, show some slight tendency toward filifery, especially in age. For these reasons, Y. madrensis clearly belongs to section Sarcocarpa, series Treculeanae McKelvey (McKelvey, 1938). Fruits of Y. rigida are dehiscent and less than half the length of those of Y. madrensis.

Fig. 1. Fruits of Y. madrensis.

Fig. 2. Seeds of Y. madrensis.

Fig. 3. Leaves of Y. madrensis, harvested for use as cordage.

Gentry (1972) reported that the Warihio of the Sierra Charuco call this species "soco" and use the roots as a source of soap and eat the tender, green fruits. The species is also an important economic plant to the Pima, who use the leaves extensively for cordage, especially for tying together bundles of maize stalks for winter storage (Fig. 3). The leaves are harvested by cutting them near the base, then split from the proximal end into quarters. These strands are then tied end to end to form a cord long enough to wrap around the bundle of maize stalks. The Pima also occasionally eat mature seeds and the pulp of immature fruits, and formerly made soap from the roots.

When speaking Spanish, the residents of Nabogame refer to the plant as either "jamole" or "sahualiqui"; some people insist the latter term refers properly only to the larger Y. grandiflora Gentry present at lower elevations, while others use the two terms interchangeably for Y. madrensis. The traditional Pima term is "hoye."

References

Gentry, H. S. 1942. Rio Mayo plants. Carnegie Institution of Washington Publication 527.

--------. 1972. The Agave family in Sonora. USDA Agricultural Handbook 399.

McKelvey, S. D. 1938. Yuccas of the southwestern United States, part 1. Arnold Arboretum of Harvard University, Jamaica Plain, Massachusetts.