Orobanche valida


Madroño 1: 255. 1929.

Common names: Rock Creek broomrape
Synonyms: Aphyllon validum (Jepson) A. C. Schneider Orobanche ludoviciana var. valida (Jepson) Munz
Treatment appears in FNA Volume 17. Treatment on page 485. Mentioned on page 470, 482, 486.

Plants simple or with a few short branches, (6–)10–30 cm, relatively slender, base sometimes slightly enlarged. Roots inconspicuous, slender, unbranched or branched. Leaves few, imbricate proximally, erect; blade narrowly to broadly ovate, 5–7 mm, margins entire, apex acute to obtuse, surfaces glabrous. Inflorescences spikelike racemes, creamy white proximally, dark purple distally, simple, densely glandular-pubescent, sometimes also sparsely pilose proximally (subsp. howellii); flowers numerous; bracts ascending to recurved, narrowly lanceolate-acuminate to lanceolate-subulate, 5–10 mm, apex acuminate, densely glandular-pubescent. Pedicels 0–5 mm (to 10 mm proximally), much shorter than plant axis; bracteoles 2. Flowers: calyx dark purple externally, weakly bilaterally symmetric, (4–)6–10(–11) mm, deeply divided into 5 lobes, lobes linear-subulate, densely glandular-pubescent; corolla 12–16(–18) mm, tube dark purple, sometimes yellow to white abaxially, constricted above ovary, bent forward, glandular-pubescent; palatal folds prominent, pale yellow to white, glabrous or puberulent; lips dark purple, abaxial lip usually white to pale lavender with purple veins, abaxial lip spreading abruptly from base, 4–5 mm, lobes narrowly oblong to oblong-triangular, apex acute or bluntly pointed, adaxial lip erect or reflexed distally, 3–5 mm, lobes triangular, apex acute; filaments glabrous or with a few hairs at base, anthers included, glabrous or pilose. Capsules narrowly ovoid to oblong-ovoid, 6–9 mm. Seeds 0.2–0.4 mm.


Subspecies 2 (2 in the flora).

Orobanche valida is the rarest species in the genus in North America, occurring in two disjunct sets of populations on a few rocky mountain slopes of granite and volcanic rock in the San Gabriel and central North Coast Range mountains. It is also the most narrowly endemic species of Orobanche. The populations of the two subspecies are separated by several hundred kilometers. The host species are also unique when compared with other Orobanche species; O. valida is parasitic on Garrya (Garryaceae) and has also been reported on Eriodictyon (Hydrophyllaceae) and Quercus (Fagaceae). P. A. Munz (1930) treated O. valida as a variety of O. ludoviciana, but L. R. Heckard and L. T. Collins (1982) demonstrated its status as a species and described an additional subspecies. Because of its restricted distribution and relative rarity, O. valida should be considered for addition to California’s list of plants of conservation concern.


1 Corollas 12–14 mm, lips and distal tubes puberulent, glabrous or sparsely puberulent at constriction and proximally; palatal folds glabrous; anthers glabrous or with a few glandular hairs near connective; filaments glabrous. Orobanche valida subsp. valida
1 Corollas 14–16(–18) mm, lips and tubes densely glandular-pilose throughout; palatal folds puberulent; anthers pilose; filaments sparsely pilose at bases. Orobanche valida subsp. howellii