PHOENICAULIS Nuttall, in Torrey & A. Gray, Fl. N. Amer. 1: 89. 1838.
Ihsan A. Al-Shehbaz
Tribe: Boechereae Al-Shehbaz, Beilstein & E. A. Kellogg, Pl. Syst. Evol. 259: 111. 2006.
Name derivation: Greek phoenix, date palm tree, and kaulos, stem, in reference to the stem with petiolar remains resembling those of the date palms.
Herbs, perennial, with well-developed, woody caudex. Trichomes finely dendritic. Multicellular glands absent. Stems erect, 1 or few from caudex, simple. Basal leaves long petiolate, rosulate, simple, entire, persistent; cauline leaves sessile, auriculate, simple, entire. Racemes many-flowered, ebracteate, corymbose, elongated considerably in fruit; rachis straight; fruiting pedicels slender, divaricate, persistent. Sepals oblong, free, caducous, erect, glabrous, subequal, base of lateral pair saccate. Petals purple or lavender, erect, longer than sepals; blade spatulate to oblanceolate, apex obtuse; claw undifferentiated from blade, rather short, glabrous, unappendaged, entire. Samens 6, slightly exserted, tetradynamous; filaments wingless, unappendaged, glabrous, free, not dilated at base; anthers oblong, obtuse at apex. Nectar glands confluent, lateral ones annular, median glands present. Ovules (6–)8–16(–18) per ovary, placentation parietal. Fruit dehiscent siliques, lanceolate to linear, latiseptate, not inflated, unsegmented; valves papery, with a prominent midvein and often conspicuous lateral veins, glabrous, not keeled, not torulose, wingless, unappendaged; gynophore obsolete to 2 mm; replum rounded, visible; septum complete, opaque, veinless; style distinct, persistent; stigma capitate, entire, unappendaged. Seeds uniseriate, wingless, oblong to broadly ovate, slightly flattened; seed coat smooth, not mucilaginous when wetted; cotyledons accumbent. x = 7.
Monospecific: W United States.