Orobanche ludoviciana
Orobanche fasciculata
Louisiana broomrape
cluster broomrape
inconspicuous to conspicuous (often forming an amorphous mass), slender, usually branched.
inconspicuous, slender or stout, unbranched or few-branched.
several to numerous, appressed;
blade lanceolate to lanceolate-ovate, 5–10 mm, margins entire, apex acute, surfaces sometimes glandular-pubescent.
few to several, erect or reflexed;
blade oblong-ovate to ovate-triangular or awl-shaped, (4–)6–12(–15) mm, margins entire, apex acute or acuminate, surfaces glandular-pubescent distally.
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.
fascicles, irregular corymbs, or short racemes of (1–)6–15(–20) flowers at stem or branch tips, light yellow to yellow or tinged pinkish to reddish purple, simple, densely glandular-pubescent, sometimes glabrescent proximally;
bracts erect or ± spreading, oblanceolate to oblong, lanceolate, or awl-shaped, sometimes ovate, 7–12 mm, apex acute, sometimes acuminate, moderately to densely glandular-pubescent.
0–15 mm, much shorter than plant axis;
bracteoles 2.
10–70(–150) mm, proximal as long as or ± longer than plant axis, distal sometimes shorter;
bracteoles 0.
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 light yellow to orangish yellow, tan, or grayish tan, often purplish tinged distally, sometimes entirely pinkish purple to reddish purple or dark purple, ± radially symmetric, (4–)6–12(–18) mm, divided into 5 subequal lobes, lobes shorter than to slightly longer than tube, triangular to subulate-triangular, moderately to densely glandular-pubescent;
corolla (11–)14–30(–38) mm, tube white to cream or yellow, purplish tinged, or pinkish purple to reddish purple, sometimes with darker pink, purple, or brown veins, slightly to moderately constricted above ovary, ± bent forward, glabrate or glandular-pubescent;
palatal folds ± prominent, usually yellow, moderately to densely glandular-pubescent;
lips yellow or pinkish purple to reddish purple, rarely white, sometimes with darker purple veins, abaxial lip ± spreading, 3–6(–9) mm, lobes oblong-obovate to nearly round, sometimes oblong-elliptic, apex rounded or ± pointed, sometimes shallowly emarginate, adaxial lip slightly to moderately spreading or recurved, (2–)3–6(–9) mm, lobes oblong-ovate to nearly round, sometimes oblong-elliptic, apex rounded or ± pointed;
filaments glabrous, anthers included, glabrous or villous-tomentose.
ovoid, 6–13 mm.
ovoid to oblong-ovoid, 6–12 mm.
0.3–0.5 mm.
0.2–0.5 mm.
= 48.
= 48.
Orobanche ludoviciana
Orobanche fasciculata
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.)
Similar to Orobanche uniflora, O. fasciculata forms a polymorphic complex that may involve cryptic species. However, unlike O. uniflora, infraspecific taxa in O. fasciculata lack strong correlations with morphology, geography, and host ranges; they are not recognized here. Previously, D. M. Achey (1933) separated the species into three varieties based mainly on plant color and flower size. In her unpublished thesis, K. C. Watson (1975) expanded this to four subspecies but circumscribed her taxa differently. Both authors noted morphological overlap among taxa.
Of particular interest is a series of populations from California and adjacent Oregon [always parasitic on Galium (Rubiaceae)] to which Watson applied the manuscript name "subsp. uniflorioides" and that, in many ways, are morphologically intermediate between Orobanche fasciculata and O. uniflora. Recently, A. E. L. Colwell et al. (2017) segregated these under the name Aphyllon epigalium Colwell & A. C. Schneider. They are distinctive in having typically two to four flowers per stem, usually cream to yellow corollas (sometimes tinged with pink or purple), including the palatal folds, and glandular (versus ciliolate) corolla margins. Colwell et al. went further in subdividing their new species into two subspecies, segregating plants with somewhat smaller, cream-colored corollas having at most slightly recurved lips as subsp. notocalifornicum A. C. Schneider & Colwell and retaining plants with somewhat larger, yellow corollas with spreading lobes as subsp. epigalium. This treatment is tentative, pending further research into the population genetics within the entire complex.
Most references suggest that Orobanche fasciculata uses a broad range of hosts. However, there are four main genera of host plants: Artemisia (Asteraceae), Phacelia (Hydrophyllaceae), Eriodictyon (Namaceae), and Eriogonum (Polygonaceae). As noted above, a morphologically distinctive set of populations parasitizes Galium. Other less commonly reported hosts include Ericameria and Eriophyllum (Asteraceae), Atriplex and Grayia (Chenopodiaceae), Convolvulus (Convolvulaceae), Arctostaphylos (Ericaceae), Mirabilis (Nyctaginaceae), Pinus (Pinaceae), grasses (Poaceae), Delphinium (Ranunculaceae), Adenostoma, Prunus, and Purshia (Rosaceae), and Vitis (Vitaceae). Some minor hosts are listed based only on specimen label data and require confirmation.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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