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Plant Highlight: Yucca rigida

April 2016

Yuccas in general have spiky rosettes of sword-like leaves, but they range from stemless to stout-trunked. One of those with a trunk is Yucca rigida, from north-central Mexico. Its area of occurrence lies in the southwestern part of the Chihuahuan Desert, in southeastern Chihuahua, northeastern Durango and the southwestern corner of Coahuila.

Yucca rigida can have an unbranched trunk, but it usually branches a few times to eventually become a tree up to about 15 feet high (4.5 m) with several heads (up to about 10 in a well-branched specimen). Plants tend to hold on to their old leaves, which bend downward as they age and end up making a skirt which covers the entire length of the trunk. The pale blue-gray leaves are rigid (though not thick enough to be succulent) and from 1 to 2 feet or so in length (.3 to .6 m).

Yucca rigida is spring-flowering, typically blooming in April and May at the Ruth Bancroft Garden with hundreds of creamy-white waxy flowers. The lowest flowers of the inflorescence are usually between the leaf tips, but sometimes the flower stalk is long enough that the whole rounded to oval head of flowers is just above the leaves. The flowers angle downward, so that one may look up into them from below.

Like other Yucca species, Y. rigida is pollinated by moths, and after being pollinated the flowers develop into short-cylindrical pods with pointed tips. After a couple of months, the capsules dry and split open to release the black seeds. Unfortunately, the pollinating moths are not present at the Ruth Bancroft Garden, so our plants do not make capsules.