Styrax officinalis var. redivivus

In the 1750s, Linnaeus described plant species that were known to him from the wild and then cultivated in western Europe, during a time when California native plants had not yet been collected for scientific or horticultural use. But a species native to southern Europe turned out to be also a native shrub of Southern California, Styrax officinalis L. var. redivivus (Torrey) H. Howard (Family Styracaceae). Indeed, styrax was the Greek name given to that plant by Theophrastus, the Father of Medicine, because the Mediterranean form of this species provided gum storax from the bark. Our homegrown variety redivivus is known as snowdrop bush or California storax.

My acquaintance with snowdrop bush began in graduate school-30 plus years ago. That was when Dr. Robert F. Thorne, my taxonomy professor in Claremont, California, took a group of us in search of this chaparral shrub at a locality in the San Gabriel Mountains of western San Bernardino County. It had been reported but not seen in that area for a very long time. We drove to the site, which had been burned by a fairly recent fire, hiked a couple minutes, and came upon a population of Styrax in full flower. Joy. Imagine then a reprise, about a quarter century later, when I came upon a plant in a gallon container at the Theodore Payne Foundation; I bought it, borrowed an MEMBG shovel, and planted it in the Med Section next to the wrought iron fence. Although I am known as a person with minimal horticultural skills,the plant has survived and now, 1.5 meters tall, flowers each spring beginning in March in its Westwood foster home.

Styrax officinalis has a simple, relaxed form. Its very thin leaves are elliptic, 5(10 cm by 3.5(5.5 cm, and they have a wavy, entire margin. The petioles are short, on our specimen rarely more than half a centimeter in length. Our plant is "see-through" because the alternate leaves are widely spaced (4(6 cm) along the thin, reddish stems. Probably the most noteworthy feature is that each leaf has associated with it a small but conspicuous, whitish green axillary bud, because in the Styracaceae the axillary buds are stalked. A tight, dark bark covers the basal stems.

The flowers also exhibit that relaxed form. Styrax officinalis produces a short, few-flowered inflorescence that terminates a short lateral shoot. Our specimen tends to have clusters (racemes) generally with two to five flowers, with the oldest flower at the base and the youngest at the top. Buds and flowers are somewhat pendent. From the light green stalk, called a pedicel, arises a whiter, crownlike calyx consisting of fused sepals, truncated but with five or more teeth; and arising past the calyx is the pure white corolla. A side view of the drooping flower looks like a bell (i.e., campanulate) or an A-line wedding gown. In fact, flowers of the related genus Halesia from the southeastern United States are called silverbells. The corolla, opening to about 3 cm, is composed of five or six petals, which are fused at their bases into a very short tube. Within are found 9 to 12 stamens with white filaments and light orange-yellow anthers; the filaments are relatively broad and fused (connate) at the base in a ring and also fused (adnate) to the short tube at the base of the corolla. Through the anthers, the white style passes and projects nearly a centimeter from the anthers, placing the stigma in a position to touch the pollinator when it first arrives at the flower. The strong, sweet fragrance, white design, and exserted style and stigma all suggest that this plant is adapted to hawkmoth pollination (see MEMBG newsletter 4 spring). The superior ovary develops into a dry fruit, although none so far have been seen at MEMBG. We can hope.

Three decades ago there was extensive discussion about intercontinental disjunctions. A disjunction is a gap in the distribution of a group. Certain genera and a handful of species have very large discontinuities in their range, some having gaps of ten to twenty thousand kilometers! Styrax officinalis is one of those, being at approximately the same latitude but nine time zones away: California to Italy. This has been termed by Dr. Thorne (in 1972) as the Mediterranean-American disjunction. How and when the populations of this species became so separated is still a matter of speculation, because there are other plants of the Mediterranean region that have very closely related species in California. Other species of Styrax also occur in North America; for example, there are four native species in the flora of Texas, and the many of species in the genus are native to eastern Asia. The only reasonable conclusion is that this genus was once widely distributed across the Northern Hemisphere and became restricted to certain smaller zone.

Uses of natural products from bark of Styrax date back at least to the Sumerians, who incorporated the terpenoid resin storax into a variety of medicinal preparations, such as liniments and ointments, applied to sores, aches, and infections. Some accounts say that the inner bark was crushed, and then hot water was used to extracted the terpenoids, whereas others mention boiling the bark and skimming the insoluble resin scum before pressing the inner bark for more extract. From that storax is refined into an opaque liquid having the viscosity of honey and the fragrance of balsam. The more common source of storax now is sweet gum, Liquidambar styraciflua (Family Hamamelidaceae), a native tree of North America.

ARTHUR C. GIBSON, MEMBG Director

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