Montana Field Guide

PLANTS: A short, hemi-parasitic, herbaceous perennial plant that arises from a branched caudex. Plants grow 5-20 cm tall and are multi-stemmed. Foliage is green with short hairs (glabrate to puberulent).

LEAVES: Arranged alternately on the stem. Leaves are green (occasionally reddish at base), narrowly lanceolate, 1–3 cm long, and usually entire along the margins. The lowest leaves are smallest. Leaves generally feature prominent veins and a puberulent surface.

INFLORESCENCE A dense, terminal, bracteate spike, usually less than 4 cm long. The inflorescence is viscid-villous. Bracts are yellowish-white to green, sometimes purplish-tipped, narrowly ovate, entire or with a pair of small lateral lobes. The calyx is 15–23 mm long with subequal primary clefts and rounded ultimate lobes of 1–3 mm long. The corolla is whitish, 18–25 mm long with the galea 5–9 mm long and the lower lip 2–4 mm long.

Sources: Giblin et al. [eds.] 2018; Lesica et al. 2012; Holmgren in Intermountain Flora 1984.

Castilleja is a difficult genus because hybridization and allopolyploid speciation (containment of multiple sets of chromosomes that are derived from different species) fuzz a species’ characteristics (Giblin et al. [eds.] 2018).

To identify Castilleja species, it is important to (Giblin et al. [eds.] 2018):
* note colors of the bract, calyx, and corolla while in the field, and
* press many bracts, calyces, and corollas separately to show their shapes.

Western Indian Paintbrush - Castilleja occidentalis, native:
Hybridizes with Castilleja rhexifolia resulting in flowers colored from white to purple (Lesica et al. 2012). In Alberta Canada, plants intergrade with Castilleja sulphurea (Moss and Packer 1983).
* Plants short, 10-20 cm tall.
* Bracts are yellow-white to green, sometimes purple-tipped.
* Upper third of the stem with green, mostly entire, non-lobed leaves.
* Uppermost leaves narrowly lanceolate.
* Inflorescence with viscid-villous hairs.
* Montana plants occur in upper subalpine to alpine zones.

Rhexia-leaf Indian Paintbrush - Castilleja rhexifolia, native:
* Bracts are reddish-purple.
* Corolla green to red.
* Upper stem with green, entire, non-lobed leaves (except sometimes the uppermost).
* Primary clefts of the calyx are about equal.
* Galea is 8-12 mm. Lower corolla lip is 1-4 mm.
* Inflorescence with viscid-villous hairs.
* Montana plants occur in subalpine to alpine zones.

Sulphur Indian Paintbrush - Castilleja sulphurea, native:
* Bracts and corolla are yellow.
* Foliage is glabrous to puberulent
* Primary clefts of the calyx are slightly deeper adjacent to the corolla lip than compared to the back.
* Galea is 6-10 mm. Lower corolla lip is 1-3 mm.
* Inflorescence with glandular-villous hairs.
* Montana plants occur in valleys to subalpine zones.

Moist meadows and moraine in the upper subalpine and alpine zones in Montana (Lesica et al. 2012).

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus appositus, Bombus bifarius, Bombus fervidus, Bombus flavifrons, Bombus melanopygus, Bombus sylvicola, Bombus occidentalis, and Bombus kirbiellus (Macior 1974, Thorp et al. 1983, Bauer 1983, Mayer et al. 2000, Wilson et al. 2010, Pyke et al. 2012, Koch et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014).