Orobanche ludoviciana
Orobanche minor
Louisiana broomrape
clover broomrape, common broomrape, hellroot, lesser broom-rape
inconspicuous to conspicuous (often forming an amorphous mass), slender, usually branched.
usually conspicuous (often forming a globular mass), very slender, usually branched.
several to numerous, appressed;
blade lanceolate to lanceolate-ovate, 5–10 mm, margins entire, apex acute, surfaces sometimes glandular-pubescent.
several to numerous, loosely ascending to spreading, imbricate only near stem base;
blade lanceolate to oblong-ovate or triangular-ovate, 6–20 mm, margins entire, apex acute to acuminate, surfaces moderately to densely glandular-pubescent.
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.
spikes, reddish brown to purple or yellow, simple, sparsely to densely glandular-pubescent;
flowers numerous, axis visible between flowers;
bracts slightly reflexed, narrowly lanceolate, 6–17 mm, apex attenuate, glandular-pubescent.
0–15 mm, much shorter than plant axis;
bracteoles 2.
0–0.8 mm (rarely to 30 mm in proximalmost flowers);
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 yellow or brownish red to brownish purple, strongly bilaterally symmetric, (6–)8–12 mm, deeply divided into 2 lateral lobes (rarely with an additional vestigial abaxial lobe), lobes entire or asymmetrically divided into 2 teeth or short lobes, these much shorter than tube, lanceolate to subulate-attenuate, ± glandular-villous;
corolla 10–19 mm, tube white to pale yellow, not or only slightly constricted above ovary, ± curved, glandular-puberulent;
palatal folds prominent, yellow to nearly white, usually glabrous;
lips similar in color to tube, more commonly purplish tinged and/or veined, sometimes more strongly so externally, abaxial lip spreading abruptly from base, 3–4 mm, lobes broadly ovate to ± semiorbiculate (this sometimes difficult to observe because of the crinkled, erose-crenulate margins and overlapping sinuses), apex rounded or shallowly emarginate, adaxial lip erect or curved outward at tip, 3–5 mm, lobes shallow, ± semiorbiculate, apex broadly rounded;
filaments sparsely pubescent, distal hairs gland-tipped, anthers included, glabrous or tomentulose.
ovoid, 6–13 mm.
ovoid to oblong-ovoid, 5–9 mm.
0.3–0.5 mm.
0.2–0.4 mm.
= 48.
= 38.
Orobanche ludoviciana
Orobanche minor
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.)
Orobanche minor has been documented most frequently parasitizing introduced clovers (mainly Trifolium arvense and T. repens), and collected rarely on Crotalaria (J. W. Thieret 1971) and Vicia. It also has been recorded, at least historically, on a variety of cultivated hosts in the region, including hemp, carrots (Daucus carota), tobacco, geraniums (Pelargonium spp.), and Petunia spp. Allegedly, the species is toxic to livestock (Thieret). The sole specimen from Idaho (J. A. Allen s.n., 1875, NY) lacks locality data; if the provenance is correct, the elevational range would be extended upward.
European authors have recognized a number of infrataxa and segregates; for example, F. J. Rumsey and S. L. Jury (1991) provisionally accepted four varieties of Orobanche minor as occurring in the British Isles. However, they noted that little is known about cytological and morphological variation within the complex. Thus, it seems inappropriate to apply an infraspecific classification to the North American plants.
A single historical specimen (J. C. Nelson 3337, 25 August 1920, GH) collected from ship’s ballast in the Linnton area of Portland, Oregon, is an unusually stout plant with apparently pale corollas and filaments relatively densely pubescent toward their bases. This plant may represent a record of Orobanche loricata Reichenbach, a European species that parasitizes mainly Picris and other Asteraceae, and does not affect any crop plants. However, specimen condition precludes definitive determination, and the label does not list a host species. Other materials from Oregon have the typical morphology of O. minor.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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