Orobanche pinorum

Plants simple or few-branched from near base, 10–40 cm, slender, base enlarged. Roots conspicuous (usually forming an irregularly globular mass), stout, unbranched. Leaves numerous, appressed proximally, spreading distally; blade lanceolate to oblong-ovate or triangular-ovate, 6–20 mm, margins entire, apex acute to acuminate, surfaces usually glabrous. Inflorescences open, cylindric panicles, ochraceous, red-brown, purple or purple streaked, yellow, or cream-white, loosely branched, rarely simple, cinereous glandular-puberulent; flowers numerous, widely spaced proximally, clustered distally; bracts reflexed, narrowly lanceolate, 3–6 mm, apex acuminate, moderately glandular-puberulent. Pedicels 0–2(–6) mm, much shorter than plant axis; bracteoles 2. Flowers: calyx yellow, brown, or purple, ± radially symmetric, 5–8 mm, divided into 5 subequal lobes, lobes slightly shorter than to ca. as long as tube, subulate, puberulent; corolla 13–19 mm, tube white, cream, or light yellow, sometimes reddish brown to purple tinged or with reddish brown or purple veins, strongly constricted above ovary, bent forward, glandular-pubescent; palatal folds not prominent, pale or light yellow, glabrous; lips externally white, cream, or light yellow, sometimes reddish or purplish tinged distally or with reddish brown to purple veins, internally reddish brown to purple, sometimes pale with reddish brown or purple veins, abaxial lip spreading, 3–4 mm, lobes narrowly lanceolate, apex rounded, adaxial lip spreading, 3–4 mm, lobes lanceolate, apex rounded, acute, or emarginate; filaments with ring of hairs at base, anthers included or 1 pair exserted, glabrous or sparsely pubescent. Capsules ovoid, 6–7 mm. Seeds 0.3–0.5 mm. 2n = 48.

Phenology: Flowering Jul–Sep.
Habitat: Dry coniferous forests, rocky slopes.
Elevation: 200–2500 m.

B.C., Calif., Idaho, Nev., N.Mex., Oreg., Wash.

Discussion

Orobanche pinorum is unusual in appearance as the stem and inflorescence axis are often markedly darker in color than the flowers.

Orobanche pinorum is chiefly host-specific on Holodiscus discolor (Rosaceae) and is largely sympatric with that species. There are a few occurrences outside the range of H. discolor where it is reported on other species of Holodiscus. Unverified reports on herbarium sheets of parasitism on various conifers exist. Disjunct locations in Nevada and New Mexico are noteworthy, because they suggest that this species may be found in appropriate habitat in the intervening Great Basin territory.

Selected References

None.

Lower Taxa