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Louisiana broomrape

Cooper's broomrape, desert broomrape

Habit Plants simple or few-branched, 7–40(–54) cm, usually stout, base enlarged in robust specimens. Plants simple, branched, or multiple stems from host attachment, 5–45 cm, stout, sometimes slender, base usually enlarged.
Roots

inconspicuous to conspicuous (often forming an amorphous mass), slender, usually branched.

usually relatively conspicuous (often forming an irregular mass), slender, branched.

Leaves

several to numerous, appressed;

blade lanceolate to lanceolate-ovate, 5–10 mm, margins entire, apex acute, surfaces sometimes glandular-pubescent.

numerous, appressed;

blade ± lanceolate to broadly ovate, 6–12 mm, margins entire, apex acute or obtuse, surfaces sometimes glandular-pubescent.

Inflorescences

spikelike racemes, purple, lavender, or pallid distally, rarely yellow, sometimes branched, glandular-pubescent;

flowers numerous;

bracts ± reflexed, lanceolate, 8–12 mm, apex acute or attenuate, densely glandular-pubescent.

spikelike racemes, purple, usually branched, densely glandular-pubescent, sometimes appearing canescent;

flowers numerous;

bracts erect to reflexed, lanceolate to linear, 5–12 mm, apex acuminate, obtuse, or acute, glandular-pubescent.

Pedicels

0–15 mm, much shorter than plant axis;

bracteoles 2.

0–30 mm, much shorter than plant axis;

bracteoles 2.

Flowers

calyx purple, lavender, or pallid, weakly bilaterally symmetric, 8–14 mm, deeply divided into 5 lobes, lobes lanceolate-subulate, glandular-pubescent;

corolla 14–20 mm, tube white to pallid or cream, sometimes pinkish or light purplish tinged distally, sometimes with purple veins, constricted above ovary, slightly curved forward, glandular-pubescent;

palatal folds prominent, yellow, pubescent;

lips externally white to pallid or cream, sometimes pinkish or light purplish tinged, internally pink or purple, sometimes white with purple veins, rarely light yellow, abaxial lip spreading, 3–5 mm, lobes oblong-lanceolate, apex obtuse or rounded, adaxial lip erect or slightly reflexed, 4–6 mm, lobes ovate, sometimes deltate, apex rounded or obtuse to bluntly pointed;

filaments glabrous or pilose at base, anthers included or slightly exserted, glabrous or with few woolly hairs along sutures.

calyx dark purple or lavender, weakly bilaterally symmetric, 8–12 mm, deeply divided into 5 lobes, lobes lanceolate-acute to -attenuate, densely glandular-pubescent;

corolla 15–32 mm, tube purple or lavender, rarely white, tinged with purple, constricted above ovary, bent forward, ± glandular-pubescent;

palatal folds prominent, yellow, densely pubescent;

lips dark purple to lavender, with darker purple veins, abaxial lip spreading or slightly reflexed, 3–9 mm, lobes oblong-lanceolate to narrowly ovate, apex acute, often with apiculate tooth, adaxial lip erect, reflexed, or revolute, 6–10 mm, lobes ± triangular, rarely truncate, apex acute, often with apiculate teeth;

filaments glabrous, anthers included, glabrous, sparsely villous, pubescent, or tomentulose along sutures, usually also with inconspicuous stalked glands (these minute, appearing peglike under magnification).

Capsules

ovoid, 6–13 mm.

ovoid, 6–12 mm.

Seeds

0.3–0.5 mm.

0.2–0.5 mm.

2n

= 48.

Orobanche ludoviciana

Orobanche cooperi

Phenology Flowering Apr–Aug.
Habitat Prairies, sand hills, sand dunes, eroded ground, glades, roadsides.
Elevation 0–2500 m. (0–8200 ft.)
Distribution
from FNA
CO; ID; IL; KS; MN; MO; MT; ND; NE; NM; OK; SD; TX; WA; WI; WY; AB; BC; MB; SK
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NM; NV; TX; n Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Orobanche ludoviciana is one of the most widely distributed species of Orobanche in North America. It commonly occurs in wind and water eroded habitats, principally in the Great Plains of North America and contiguous areas.

Throughout most of its range, Orobanche ludoviciana parasitizes Grindelia squarrosa and several species of Artemisia. However, at the southern limits of the range in Texas, it has been reported on Baccharis, Haploësthes, Heterotheca, and Thelesperma (Asteraceae); in Canada, Heterotheca villosa is an important host. The reports on cultivated crops (tomato and tobacco) are the result of misidentifications by P. A. Munz (1930) and should be attributed to O. cooperi and O. riparia.

The binomial Orobanche ludoviciana has often been broadly applied to several taxa in western states, including several taxa treated herein as species.

P. A. Munz (1930) inadvertently used a specimen of Orobanche riparia to describe and illustrate the corollas of O. ludoviciana as having pointed corolla lobes. This led him to include several western taxa that have pointed corolla lobes within O. ludoviciana, including taxa treated here as species: O. cooperi, O. riparia, and O. valida. L. T. Collins et al. (2009) clarified this issue, pointing out that the corolla lobes are in fact rounded.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Subspecies 3 (3 in the flora).

The hosts for Orobanche cooperi are shrubs of Ambrosia and Viguiera (Asteraceae).

L. R. Heckard and T. I. Chuang (1975) mentioned an undescribed polyploid variant (2n = 96) with smaller, shorter-lobed corollas and peltate, bowl-shaped stigmas occurs on the same hosts in southern California.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Corollas 15–18(–22) mm, lips 3–6 mm, adaxial lips reflexed or revolute; anthers glabrous or tomentulose from pollen sacs, stalked glands often few on dorsal surfaces or absent; Chihuahuan Desert.
subsp. palmeri
1. Corollas (15–)18–32 mm, lips 5–10 mm, adaxial lips erect or reflexed; anthers glabrous, sparsely villous, or pubescent, stalked glands present on dorsal surfaces, sometimes obscure, rarely absent; Sonoran Desert and adjacent portions of California and Nevada.
→ 2
2. Corollas (15–)18–22 mm, adaxial lips erect, lobes with or without apiculate teeth.
subsp. cooperi
2. Corollas 22–32 mm, adaxial lips erect or reflexed, lobes with apiculate teeth.
subsp. latiloba
Source FNA vol. 17, p. 481. FNA vol. 17, p. 484.
Parent taxa Orobanchaceae > Orobanche Orobanchaceae > Orobanche
Sibling taxa
O. arizonica, O. bulbosa, O. californica, O. cooperi, O. corymbosa, O. fasciculata, O. minor, O. multiflora, O. parishii, O. pinorum, O. ramosa, O. riparia, O. robbinsii, O. uniflora, O. valida, O. vallicola
O. arizonica, O. bulbosa, O. californica, O. corymbosa, O. fasciculata, O. ludoviciana, O. minor, O. multiflora, O. parishii, O. pinorum, O. ramosa, O. riparia, O. robbinsii, O. uniflora, O. valida, O. vallicola
Subordinate taxa
O. cooperi subsp. cooperi, O. cooperi subsp. latiloba, O. cooperi subsp. palmeri
Synonyms Aphyllon ludovicianum, Myzorrhiza ludoviciana, O. ludoviciana var. arenosa, O. multiflora var. arenosa Aphyllon cooperi, Myzorrhiza cooperi, O. ludoviciana var. cooperi
Name authority Nuttall: Gen. N. Amer. Pl. 2: 58. (1818) (A. Gray) A. Heller: Cat. N. Amer. Pl., 7. (1898)
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