Stems ascending to prostrate, 3–10 cm from a simple caudex clothed in old leaf bases. Basal leaves 15–40 mm long; the blades orbicular to rhombic, deeply few-toothed or lyrate. Stem leaves oblanceolate to spatulate, entire. Vestiture of dense, stellate hairs with branched stellae. Petals 8–12 mm long. Fruit of 2 ovate lobes, inflated, 7–11 mm high, the apical sinus deep, the basal sinus absent; style 5–7 mm long; seeds 2 per locule; pedicels spreading, straight to curved, 5–10 mm long. Our plants are subspecies dentata
(Rollins) O'Kane (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)
Flowering and fruiting in June and July with fruits maturing into August.
Only variety dentata
occurs in Montana. Variety saximontana
, which is only known from Wyoming, can be distinguished by its entire basal/rosette leaves and longer styles (3 or more times the length of the replum) vs. the toothed apical margins of the basal/rosette leaves of variety dentata
and the shorter styles (1-2 times or less the length of the replum). Another species occurring in southwest Montana is P. didymocarpa
, which differs in having deep sinuses at both the top and bottom of the fruit. The fruit of P. saximontana
is notched with only a sinus at the top.Rocky Mountain Twinpod
– Physaria saximontana
*Pedicels are spreading to straight to curved, 5–10 mm long.
*Fruits are inflated and
2-lobed, 7-11 mm high.
*Basal leaf blades are orbicular to rhombic in shape, 15–40 mm long, and deeply few-toothed or lyrate.
*Plants typically grow in limestone-derived soils of grasslands and fellfields on exposed slopes in the montane zone.Thick-leaf Bladderpod
– Physaria pachyphylla
*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.
Typically found in limestone-derived talus, fellfields, and gravelly slopes at moderate to high elevations.