Orobanchaceae image
Damon A. Smith  

Key to Wisconsin Orobanchaceae

Author: John G. Zaborsky

    • 1a. Plants non-green, lacking photosynthetic leaves 2

    • 1b.Plants green, with well-developed photosynthetic leaves 4

    • 2a.2. Bracts, pedicels, and calyces glabrous; aerial stem below the inflorescence densely covered in scale-like leaves Conopholis

    • 2b.Bracts, pedicels, and calyces sparsely to densely glandular-pubescent (sometimes only on the margins in Epifagus); aerial stem, if any, below the inflorescence with few leaves 3

    • 3a.Flowers of two kinds, the upper with well-developed 4-lobed corollas (9–) 10 (–12) mm long, the lower with calyptriform corollas that do not open; pedicels and calyces sparsely glandular-pubescent to glabrous Epifagus

    • 3b.Flowers all alike, with 5-lobed corollas 14–25 mm long; pedicels and calyces densely glandular-pubescent Aphyllon

    • 4a. Cauline leaves of fertile stems all or mostly alternate (lowermost leaves sometimes opposite and basal rosettes sometimes present) 5

    • 4b.Cauline leaves of fertile stems all or mostly opposite (may be alternate immediately below the flowers) 6

    • 5a. Leaves pinnately-lobed; corollas glabrous Pedicularis (in part)

    • 5b. Leaves entire or with 1–2 pairs of lateral lobes; corollas pubescent Castilleja

    • 6a. Leaves entire (Agalinis auriculata and some forms of Melampyrum have some leaves with a few lobes basally) 7

    • 6b. Leaves toothed or pinnately-lobed 8

    • 7a. Corollas white with yellow lips; fruit strongly compressed at its apex into a tapered beak Melampyrum

    • 7b. Corollas pink to purple; fruit spherical with rounded apex Agalinis

    • 8a. Leaves of main stem (especially middle and lower) deeply pinnately-lobed 1/3 or more to the midrib 9

    • 8b. Leaves all merely toothed, not lobed 11

    • 9a. Flowers in dense, spike-like racemes at the ends of stems and branches; stamens enclosed in the hooded upper lip of the strongly 2-lipped corollas Pedicularis (in part)

    • 9b.Flowers axillary or in racemes; corollas distinctly 5-lobed, the stamens not concealed 10

    • 10a.Corollas 25–45 (–50) mm long, inflated apically, the throats moderately to sparsely pubescent in the apical half; pedicels 4–24 (–28) mm long Aureolaria

    • 10b.Corollas 7–16 mm long, scarcely inflated, the throats densely villous throughout; pedicels 1–2 mm long Dasistoma

    • 11a.Leaves ovate to ovate-lanceolate, palmately-veined Euphrasia

    • 11b.Leaves oblong to lanceolate to linear-lanceolate, pinnately-veined 12

    • 12a. Corollas bright yellow; calyx distinctly inflated Rhinanthus

    • 12b.Corollas reddish-pink; calyx not inflated Odontites

This family was historically circumscribed to only include the non-photosynthetic holoparasitic genera.  Research using genetic data has shown that the family should include all of the hemi-parasitic genera formerly placed in the Scrophulariaceae as well as a few non-parasitic genera found outside North America.  Hemi-parasitic plants produce green leaves capable of photosynthesis but also absorb nutrients from a host plant.

Some species of this family are serious crop pests in other parts of the world and can greatly reduce yields.  It has been shown that in prairie and field communities, members of this family have a great effect on species diversity.  The parasitic plants stunt the growth of their taller hosts, allowing shorter-statured plants to become established and more easily compete.  Many of our species that are associated with prairies and savannas are quite rare and declining.