About Dudleya variegata (S.Watson) Moran
Dudleya variegata (S.Watson) Moran belongs to the subgenus Hasseanthus of the genus Dudleya. While most other members of the genus Dudleya form evergreen rosettes, the Hasseanthus subgenus has diverged into geophytic plants. Species in this subgenus have small, globose, deciduous leaves that resemble the juvenile leaves of Dudleya species outside the subgenus in both appearance and size. In this subgenus, the stem has evolved into a corm-like structure buried underground, and plants rely on starch reserves stored in the tuberous root to survive the dry season. The reduced leaves and corm-like caudex are likely paedomorphic adaptations, since most Dudleya seedlings naturally have a tuberous caudex and small, drought-deciduous leaves. This species has distinctive leaves that are often paddle or spoon-shaped with long petioles, and its inflorescences hold spreading, bright yellow flowers. Its stem takes the form of an oblong, corm-like structure. Plants can survive the summer without any water, and do not regrow leaves until moisture returns in mid-October, with new leaves emerging in November.
Morphologically, this species produces 1 to 3 rosettes from the top of its subterranean stem. Each leaf cluster measures 2–6 cm (0.79–2.36 in) wide. The buried stem itself is 1–3 cm (0.39–1.18 in) long and 3–15 mm (0.12–0.59 in) wide, with a shape ranging from roughly spherical to oblong. The leaves are deciduous in summer, generally not glaucous, and have an oblanceolate or spoon shape. Leaves measure 1–7 cm (0.39–2.76 in) long by 0.5–11 mm (0.020–0.433 in) wide; their bases are generally 1–3 mm (0.039–0.118 in) wide, and leaf tips range from acute to obtuse in shape. The peduncle is 5–20 cm (2.0–7.9 in) tall and 0.5–2 mm (0.020–0.079 in) wide, and bears 2 to 3 simple, ascending branches. These branches are 2–15 cm (0.79–5.91 in) long, and hold 3 to 11 flowers each. Flowers are held on pedicels 0.5–3 mm (0.020–0.118 in) long. Flower sepals are 2–3.5 mm (0.079–0.138 in) long and shaped deltate-ovate. Petals are 5–8 mm (0.20–0.31 in) long by 2–3.5 mm (0.079–0.138 in) wide, shaped elliptic, colored bright yellow, and end in an acute tip. Fruits are spreading, inheriting this trait from the flowers. Plants flower from April to June, and their chromosome number is 2n = 34 (n = 17).
This species is endemic to an approximately 80 km long range that extends from San Diego County, California, south into northwestern Baja California, Mexico, from Tijuana to Ensenada. It occurs in relatively small, disjunct populations from near Black Mountain Ranch in San Diego County to Ensenada. Populations have been recorded in San Diego County at Black Mountain, Kearney Mesa, Dictionary Hill, San Miguel Mountain, El Cajon, La Mesa, Fletcher Hills, Paradise Hills, Rice Canyon, Dehesa, Otay Mountain, Imperial Beach, the border near Otay Crossing, and the Silver Strand Training Complex between Imperial Beach and Silver Strand State Beach. Dudleya variegata typically grows on dry hillsides and mesas in coastal and foothill regions, usually at elevations below 300 m (980 ft). It can be found in open clearings of chamise, sage scrub, or scrub oak brush, as well as on clay lenses and in vernal pools. Associated plant species include Ferocactus viridescens, Selaginella cinerascens, and Selaginella bigelovii.
