Montana Field Guide

Stems ascending, 5–15 cm from simple caudex clothed in old leaf bases. Basal leaves 2–6 cm long, the blades ovate to obovate, usually entire. Stem leaves spatulate to oblanceolate. Vestiture of dense, stellate hairs, the stellae branched. Petals 7–12 mm long. Fruit of 2 ovate lobes, inflated, 6–10 mm wide; style 4–6 mm long; seeds 2 per locule; pedicels spreading, straight to sigmoid, 5–10 mm long (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)..

Sharpleaf twinpod - Physaria acutifolia
*Pedicels are spreading, straight, or sigmoid, 5-10 mm long.
*Fruits inflated and 2-lobed, 6-10 mm wide, and with 2 ovules per locule.
*Basal leaves ovate to obovate in shape and usually entire.

Wooly Twinpod - Physaria didymocarpa var. lanata, SOC
*Pedicels are spreading, straight, or sigmoid, 3-12 mm long.
*Fruits inflated and 2-lobed, 7-20 mm tall, and with 2-4 ovules per locule [count the stalks of the ovules].
*Basal Leaves obovate in shape with entire to coarsely dentate margins.

Thick-leaf Bladderpod – Physaria pachyphylla, SOC
*Pedicels curve upwards (ascend), 3-10 mm long.
*Fruits inflated, not 2-lobed, and narrowly elliptic to ovoid, 3-6 mm tall. Style is more than half the length of the fruit (silicle).
*Basal leaves have distinct petioles and blades. Blades are spatulate to oblanceolate in shape, nearly 1 mm thick and cupped (but not folded), and with entire margins [key characteristic].
*Plants grow on pinkish or reddish soils derived from limestone on exposed slopes and ridges in valleys.

Sandy, usually calcareous soil of open slopes in grasslands, steppe, woodlands; plains, valleys (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).