Orobanche ludoviciana
Orobanche riparia
Louisiana broomrape
river broom-rape
inconspicuous to conspicuous (often forming an amorphous mass), slender, usually branched.
inconspicuous or conspicuous (often forming an amorphous mass), slender, branched or unbranched.
several to numerous, appressed;
blade lanceolate to lanceolate-ovate, 5–10 mm, margins entire, apex acute, surfaces sometimes glandular-pubescent.
numerous, appressed;
blade broadly ovate to ovate-triangular, narrower distally, 6–9 mm, margins entire, apex acute or obtuse, surfaces glabrous.
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, lavender, or pallid, sometimes branched, glandular-pubescent, often ± viscid;
flowers numerous;
bracts usually reflexed, lanceolate, 8–15 mm, apex acute, glandular-pubescent.
0–15 mm, much shorter than plant axis;
bracteoles 2.
0–10(–12) mm, much shorter than plant axis;
bracteoles 2.
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 purple, rarely pale lavender externally, weakly bilaterally symmetric, 7–11(–13) mm, deeply divided into 5 lobes, lobes lanceolate-linear to linear-subulate, densely glandular-pubescent;
corolla (13–)15–22 mm, tube white, distally often tinged with purple or pink, or with dark purple veins, constricted above ovary, slightly to moderately bent forward, glandular-puberulent to -pubescent;
palatal folds prominent, yellow, pubescent;
lips internally ± purple or lavender, often with darker veins, abaxial lip erect to slightly spreading, 3–4 mm, lobes narrowly oblong-triangular, apex acute, adaxial lip erect to ± spreading, 4–6 mm, lobes triangular, apex acute;
filaments glabrous or pubescent at base, anthers included, glabrous or sparsely pubescent.
ovoid, 6–13 mm.
ovoid, 7–10 mm.
0.3–0.5 mm.
0.3–0.5 mm.
= 48.
= 48.
Orobanche ludoviciana
Orobanche riparia
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 riparia was formerly included in O. ludoviciana (P. A. Munz 1930). The two species can be distinguished on the basis of morphology, habitat, host associations, and phenology. Orobanche riparia appears to be more closely allied to O. cooperi than O. ludoviciana. The eastern and western populations show slight differences in color intensity and degree of pubescence.
Orobanche riparia is the only species of Orobanche that exclusively parasitizes annual hosts, including Ambrosia trifida, Dicoria canescens, and Xanthium strumarium (Asteraceae), and rarely Nicotiana tabacum (Solanaceae) (L. T. Collins et al. 2009). Its riparian distribution, entirely on sandbars, sandy banks, and silt deposits mainly of the Mississippi, Ohio, Platte, and Rio Grande rivers and tributaries, is likewise unique. Extant populations are most abundant along the Ohio and Platte rivers but are imperiled by habitat destruction along stream banks.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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