Leaves are alternate, entire, 2–5 cm in length, tapering at both ends. Flowers are small (5–8 mm), five-merous, with white petal-like
sepals, and a superior
ovary. They are arranged in short
racemes, usually no more than 10 cm long, shorter in
S. watsonii. The fruit is a
capsule 5–8 mm in diameter: it contains small (2–3 mm) black seeds with a conspicuous reddish aril. The genus has commonly been treated as belonging to the family
Phytolaccaceae, but the
APG system and
APG II system, of 2003, regard it as the sole genus of its own family, the
Stegnospermataceae and assign it to the order
Caryophyllales in the clade
core eudicots Turner et al. suggest that
S. halimifolium Bentham and
S. watsonii D.J. Rogers are actually the same species, observing that specimens from the gulf coast of
Sonora have intermediate characteristics. Whether one species or two, they are locally common all along the
Gulf of California, where they are found on the coastal strand and some inland washes, always at low elevations (less than 600 m). ==Anatomy==