Rocklady (Holmgrenanthe elisens)

Description

Holmgrenanthe petrophila (rocklady, formerly Maurandya petrophila) is a rare perennial desert plant in the plantain family (Plantaginaceae), and the sole species of the genus Holmgrenanthe. It forms low mats of branched stems growing from a woody base. The leaves have small spines along their edges. The solitary yellow flowers are tubular with five free lobes at the end, the upper two pointing backwards, the lower three projecting forwards. The species is known only from about ten locations, most in the Titus Canyon and the adjacent Fall Canyon, all within the Californian section of Death Valley National Park. It grows in limestone crevices on the canyon walls, often on the north face. Holmgrenanthe petrophila is an herbaceous perennial with fibrous roots. It is low growing with slender, branched stems arising from a woody base; as it often grows on vertical faces, the stems tend to hang down. Close relatives climb using twining leaf stalks (petioles), but H. petrophila has straight petioles, 12–27 mm (0.5–1.1 in) long. The leaves are rounded or kidney shaped with small spines or bristles along the margins (spinulose) and at the apex. They are 12–35 mm (0.5–1.4 in) long by 14–27 mm (0.6–1.1 in) wide. In its native habitat, H. petrophila flowers and fruits in spring and early summer, between April and June. The solitary flowers are borne on very short stalks (peduncles), only 1–4 mm (0.04–0.16 in) long. The green sepals are narrow, pointed and not joined, forming an urn shape around the base of the flower. They are 9–13 mm (0.4–0.5 in) long by 2–3 mm (0.08–0.12 in) wide at the base. They have small spines along their margins, like the leaves. The five petals forming the corolla are joined at their bases to form a tube 20–24 mm (0.8–0.9 in) long. The free lobes at the end of the flower are 7–12 mm (0.3–0.5 in) long and differentiated into two upper lobes, curving backwards, and three lower lobes, pointing forwards. The color of the corolla has been described as either sulfur yellow throughout or white with a yellow throat. The style and stamens stay within the flower. The four stamens are of two lengths, the upper two with filaments 12–44 mm (0.5–1.7 in) long, the lower two with filaments 7–9 mm (0.3–0.4 in) long. There is also a fifth rudimentary sterile stamen. The ovary has a single chamber with an incomplete T-shaped septum. After fertilization, a globe shaped capsule forms containing tan colored seeds.