Unknown # 39 A rare dioecious shrub in the chaparral of coastal San Diego County. The leaves are typically opposite or 3-whorled with linear or narrow-oblanceolate blades. Apetalous staminate flowers occur in clusters within the leaf axils of male shrubs, each consisting of 6-10 sepals and 6-10 stamens. Apetalous female flowers are attached to distinct pedicels on female shrubs, each composed of a 4-chambered ovary with 4 styles and 7-13 sepals. San Marcos Gabbro: A dark, basic intrusive rock that weathers into reddish Las Posas soils. It contains a high magnesium content compared with light-colored granites and granodiorites. Some of the most striking (and rare) endemic plants in the San Diego County (including unknown shrub #39) occur on these soils. The San Marcos Mountains along the west side of Twin Oaks Valley are composed of gabbro. Gabbro outcrops are excavated and used for polished counter tops and tiles. Thick gabbro table tops are used to support delicate scientific instruments. The Merriam Mountains on the east side of Twin Oaks Valley are composed of prominent boulders of exfoliating Woodson Mt. Granodiorite. The Palomar "P" hill is composed of Santiago Peak Volcanic rock. This dark, fine-grained Jurassic age rock is very resistant to erosion and forms some of the steep roads well-known to bicyclists. San Marcos Gabbro is a basic, intrusive, igneous rock that weathers and oxidizes into reddish Las Posas soils. Some of the most interesting endemic plants in San Diego Country occur on these soils. A rare endemic shrub (Tetracoccus ilicifolia) on rugged Tetracoccus Ridge in the Panamint Range overlooking Death Valley. The leaves of this species resemble those of holly (Ilex), hence the specific epithet "ilicifolia."  Return To Table Of Plant Unknowns  All text material & images on these pages copyright © W.P. Armstrong