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cancer- or squaw-root, cancer-root

Habit Herbs, perennial; achlorophyllous, holoparasitic, with perennial, tuberlike underground vegetative structure attached to host root, dark brown or black, with a sclerenchymatous, knobby surface, roots absent.
Stems

erect, yellow, brown, or black, fleshy, glabrous.

Leaves

cauline, spiral, tightly imbricate;

petiole absent;

blade stiffly chartaceous, margins entire or minutely erose or ciliate.

Inflorescences

terminal, compact racemes;

bracts present.

Pedicels

present;

bracteoles present, sometimes absent.

Flowers

sepals 2, 4, or 5, calyx bilaterally symmetric, tubular, divided abaxially, not divided adaxially, lobes lanceolate;

petals 5, corolla yellow, strongly bilabiate, tubular, arching forward, abaxial lobes [1–]3, adaxial 2, adaxial lip notched;

stamens 4, didynamous, exserted, filaments glabrous or hairy at base;

staminode 0;

ovary 1-locular, placentation parietal;

stigma disciform-crateriform or 2–4-lobed.

Capsules

indehiscent.

Seeds

300–600, glossy tan, brown, or black, irregularly ellipsoid or angled, wings absent.

Conopholis

Distribution
from USDA
e North America; Mexico; Central America; sw North America
[BONAP county map]
Discussion

Species 3 (2 in the flora).

Five species have been described in the genus; most authors accept Conopholis as including only from one to three species (R. R. Haynes 1971; A. G. Rodrigues et al. 2011, 2013). All taxa in the genus are strikingly similar morphologically. Differences in scale leaves, floral bracts, flowers, vestiture, and plant size have been used to separate species and varieties; the variability of these characters within taxa occasionally exceeds between-taxon differences. There is considerable overlap in any character set used to separate taxa. J. W. Thieret (1971) suggested that all taxa could be considered conspecific. Molecular and morphological studies by Rodrigues et al. (2011, 2013) provided strong evidence that three species should be recognized. The third taxon, C. panamensis Woodson, is known only from Central America. Hosts are all members of Quercus (Fagaceae).

Conopholis fruits develop a woody texture at maturity. Although members of the family are generally stated to produce capsular fruits, those of Conopholis generally remain indehiscent until degraded by either physical abrasion or invasion by predatory insects, such as ants. Seed dispersal tends to be of two types: short-range dispersal by the action of gravity, wind, and/or water following the breach of the wall; and longer-range dispersal following ingestion of the plants by various mammals.

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

Key
1. Bracts glabrous, lanceolate, mostly concealing calyces, margins entire or minutely erose, not ciliate; leaves glabrous or minutely hairy along margins, triangular to broadly lanceolate; calyces 3–8 mm, lobe apices acute; corollas 8–14 mm; anthers glabrous.
C. americana
1. Bracts glandular-pubescent, narrowly lanceolate, mostly not concealing calyces, margins entire, glandular-ciliate; leaves mostly glandular-pubescent, triangular to narrowly lanceolate; calyces 6–9 mm, lobe apices obtuse; corollas 14–20 mm; anthers sparsely pilose or glabrous.
C. alpina
Source FNA vol. 17, p. 461. Authors: L. Turner Collins, Alison E. L. Colwell, George Yatskievych.
Parent taxa Orobanchaceae
Subordinate taxa
C. alpina, C. americana
Name authority Wallroth: Orobanches Gen. Diask., 78. (1825)
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