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Rollins' twinpod

Snake River or creeping twinpod, Snake River twinpod

Habit Perennials; (compact); caudex usually simple, (cespitose); (silvery) pubescent throughout, trichomes 6–8-rayed, rays furcate near base, fused at base, (umbonate, strongly tuberculate throughout). Perennials; caudex usually branched, (rhizomelike, cespitose); densely (silvery) pubescent, trichomes (often stalked, appressed), several-rayed, rays furcate or bifurcate, (umbonate, strongly tuberculate throughout).
Stems

several from base, decumbent, (unbranched, slender), 0.5–1 dm.

several from base, ± erect, exceeding basal rosette by ± 0.5 dm.

Basal leaves

(strongly rosulate);

blade usually oblanceolate or broader, sometimes triangular, 2–3.5 cm (width 5–10 mm), margins entire or with 1 or 2 broad teeth, (apex acute).

(forming a strong rosette; long-petiolate);

blade oblanceolate to ovate or orbicular, (1.5–)2–4(–8) cm, (base usually abruptly tapering to petiole), margins entire.

Cauline leaves

blade oblanceolate, 1–1.5 cm (width 2–4 mm), margins entire, (apex acute).

blade oblanceolate, 1–2 cm, margin entire, (apex acute).

Racemes

congested, (elongated moderately in fruit).

congested, (greatly exceeding leaves).

Flowers

sepals linear, 5–7 mm;

petals spatulate, 8–10 mm, (apex often somewhat truncate).

sepals often keeled, 6–8 mm;

petals spatulate, 8–10 mm.

Fruiting pedicels

(spreading, straight or somewhat sigmoid), 5–8 mm.

(spreading, straight or slightly curved), 7–11 mm.

Fruits

(erect), didymous, suborbicular, inflated, 2–5(–8) × 4–8(–10)mm, (coriaceous, base slightly cordate or nearly obtuse, sinus obsolete or absent, apical sinus broad and deep);

valves (retaining seeds after dehiscence), pubescent, trichomes appressed, (silvery on ovaries and immature fruit);

replum obovate to oblong, as wide as or wider than fruit, rarely somewhat constricted basally, apex obtuse;

ovules 4 per ovary;

style 5–7 mm.

didymous, highly inflated, 8–22 × 10–25 mm, (papery, basal and apical sinuses deep);

valves (retaining seeds after dehiscence), densely pubescent, trichomes appressed;

replum linear to oblong, as wide as or wider than fruit;

ovules 8 per ovary;

style 7–9 mm.

Seeds

slightly flattened.

flattened.

2n

= 8.

= 16.

Physaria rollinsii

Physaria integrifolia

Phenology Flowering May–Jun. Flowering (May-)Jun–Jul(-Aug).
Habitat Sagebrush, granitic talus, open knolls, limestone chiprock, steep slopes, clay banks, near granite boulders Calcareous hills and slopes, shale-limestone cliffs, bare steep slopes, red clay banks, shale
Elevation 2300-2500(-3900) m (7500-8200(-12800) ft) 1900-2700 m (6200-8900 ft)
Distribution
from FNA
CO
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; MT; WY
[BONAP county map]
Discussion

Physaria integrifolia has traditionally been recognized as a variety of P. didymocarpa, but it is morphologically and ecologically quite distinctive. Variety monticola (no combination has been made at subspecific rank) is not recognized here; it is considered another example, in the genus, of caudices elongating in response to shifting substrates.

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

Source FNA vol. 7, p. 661. FNA vol. 7, p. 644.
Parent taxa Brassicaceae > tribe Physarieae > Physaria Brassicaceae > tribe Physarieae > Physaria
Sibling taxa
P. acutifolia, P. alpestris, P. alpina, P. angustifolia, P. arctica, P. arenosa, P. argyraea, P. arizonica, P. aurea, P. bellii, P. brassicoides, P. calcicola, P. calderi, P. carinata, P. chambersii, P. cinerea, P. condensata, P. congesta, P. cordiformis, P. curvipes, P. densiflora, P. didymocarpa, P. dornii, P. douglasii, P. eburniflora, P. engelmannii, P. eriocarpa, P. fendleri, P. filiformis, P. floribunda, P. fremontii, P. garrettii, P. geyeri, P. globosa, P. gooddingii, P. gordonii, P. gracilis, P. grahamii, P. hemiphysaria, P. hitchcockii, P. humilis, P. integrifolia, P. intermedia, P. kingii, P. klausii, P. lata, P. lepidota, P. lesicii, P. lindheimeri, P. ludoviciana, P. macrocarpa, P. mcvaughiana, P. montana, P. multiceps, P. navajoensis, P. nelsonii, P. newberryi, P. obcordata, P. obdeltata, P. occidentalis, P. oregona, P. ovalifolia, P. pachyphylla, P. pallida, P. parviflora, P. parvula, P. pendula, P. pinetorum, P. prostrata, P. pruinosa, P. pulvinata, P. purpurea, P. pycnantha, P. rectipes, P. recurvata, P. reediana, P. saximontana, P. scrotiformis, P. sessilis, P. spatulata, P. subumbellata, P. tenella, P. thamnophila, P. tumulosa, P. valida, P. vicina, P. vitulifera
P. acutifolia, P. alpestris, P. alpina, P. angustifolia, P. arctica, P. arenosa, P. argyraea, P. arizonica, P. aurea, P. bellii, P. brassicoides, P. calcicola, P. calderi, P. carinata, P. chambersii, P. cinerea, P. condensata, P. congesta, P. cordiformis, P. curvipes, P. densiflora, P. didymocarpa, P. dornii, P. douglasii, P. eburniflora, P. engelmannii, P. eriocarpa, P. fendleri, P. filiformis, P. floribunda, P. fremontii, P. garrettii, P. geyeri, P. globosa, P. gooddingii, P. gordonii, P. gracilis, P. grahamii, P. hemiphysaria, P. hitchcockii, P. humilis, P. intermedia, P. kingii, P. klausii, P. lata, P. lepidota, P. lesicii, P. lindheimeri, P. ludoviciana, P. macrocarpa, P. mcvaughiana, P. montana, P. multiceps, P. navajoensis, P. nelsonii, P. newberryi, P. obcordata, P. obdeltata, P. occidentalis, P. oregona, P. ovalifolia, P. pachyphylla, P. pallida, P. parviflora, P. parvula, P. pendula, P. pinetorum, P. prostrata, P. pruinosa, P. pulvinata, P. purpurea, P. pycnantha, P. rectipes, P. recurvata, P. reediana, P. rollinsii, P. saximontana, P. scrotiformis, P. sessilis, P. spatulata, P. subumbellata, P. tenella, P. thamnophila, P. tumulosa, P. valida, P. vicina, P. vitulifera
Synonyms P. didymocarpa var. integrifolia, P. integrifolia var. monticola
Name authority G. A. Mulligan: Canad. J. Bot. 44: 1663, fig. 2, plate 1, fig. 4. (1966) (Rollins) Lichvar: Madroño 31: 203. (1984)
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