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Plant Highlight: Yucca linearifolia
By Brian Kemble
Naming of the species
Yucca species typically have long sword-like leaves, but in some species the leaves are so narrow as to look needle-like. An example is Yucca linearifolia, described as a species by Karen Husum Clary in 1995. This plant had earlier been named as Yucca rostrata var. linearis by William Trelease in 1907, but it belongs in an entirely different section of the genus and is not at all closely related to Yucca rostrata, so it was eventually re-named as a separate species. While some species of Yucca have dry capsules (as does Y. rostrata), others have fleshy fruits, and Y. linearifolia is one of the latter.
Area of occurrence
Geographically, Y. linearifolia occurs in northeastern Mexico. It is found in the vicinity of Saltillo (in southeastern Coahuila), and also to the southeast in the vicinity of Galeana (in south-central Nuevo Leon). The plants in Nuevo Leon have leaves that are more bluish in color, but otherwise quite similar in appearance.
About the plant
Yucca linearifolia forms small clumps of stems from rhizomes, but the stems do not branch above ground. An older plant may have a trunk of up to nearly 12 feet (3.5 m), with the rounded head of leaves at the top and the skirt of dried old leaves extending all the way down the trunk. The trunks are fairly stout, with a diameter of up to 20 inches (50 cm), but they appear even stouter than this because they are covered in dried leaves. Only at the expanded base can the knobbly dark brown woody trunk be seen. The grayish-green to blue-green leaves are typically 13 to 15 inches long (34 to 38 cm), but may sometimes be as long as 20 inches (50 cm), ending in a small dark pointed tip. Their width is only .16 to .2 inch (.4 to .5 cm) at the middle, flattening and widening slightly in the upper half, and their margins are yellowed and minutely serrated, though this is not evident except on close inspection. While the upper side of the leaf is smooth, the underside is roughened.
About the flowers
Yucca linearifolia is spring-blooming, and like most yuccas it has panicles of creamy-white flowers. While the inflorescence is usually erect, it may sometimes bend to one side. The lowest flowers are within the crown of leaves, but most of them are above. The overall shape of the panicle is rounded or more elongated, with a total length of as much as 31½ inches (80 cm). Often the inflorescence has a “two-stage” appearance, with a smaller cluster of flowers atop the main panicle, an unusual trait. The lowest/longest floral branches are up to 6.7 inches long (17 cm), and the dangling creamy flowers have a round or oval form, with a length of .8 inch to1.4 inch (2 to 3.5 cm).
About the fruits
As mentioned, this is one of the baccate, or fleshy-fruited, species of Yucca. The green fruits either angle downward or hang straight down, and they are 1.6 to 2.7 inches long (4 to 7 cm). Sometimes they are oval, and other times shaped like a short cucumber, but with a small beak at the tip. The black bumpy-textured seeds embedded in the pulp are variable in size and shape, with those at the middle being larger and more D-shaped, and those at either end being smaller and rounder.
Plants in cultivation
Yucca linearifolia is not a difficult species to grow, needing only sharp drainage and plenty of sun. It gets summer rainfall in its home range, so occasional watering during the summer months will keep it happy in dry-summer areas such as California. It is very cold-tolerant, able to withstand lows down to 5° F or lower (-15° C). With its many-leaved symmetrical rosettes and its neat skirt of dried leaves, it makes a striking garden focal point. Note that this species, like other yuccas, has flowers pollinated by the specialized yucca moth, so it may fail to produce any fruits in an area where the moths are not present.
-Written by Brian Kemble (Curator)
The knobbly woody base of Yucca linearifolia.
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