RIGIDA Rose, 1903

Synonyms :

Cotyledon rigida  (Rose) Fedde (1904) / Echeveria rigida  (Rose) A.Berger (1930)

Subgenus Dudleya

Distribution : Mexico (southern Baja California: Sierra de la Laguna); 1450 - 1900 m.

Description (according to IHSP, 2003) :

Stems erect, to > 10 x 1 - 3.5 cm.

Rosettes 6 – 15 cm 0, with 10 - 25 leaves, to 20 in lax cushions to 25 cm in diameter.

Leaves oblong to triangular-ovate, delicately pointed, 5 - 8 x 2.5 - 4 cm, green or somewhat glaucous.

Inflorescence : Scape 30 - 60 (-75?) cm, rose-coloured to red, somewhat glaucous, inflorescence glaucous, rose-coloured to becoming red, with 2 - 3 scorpioid branches, these 4 – 23 cm, with 8 – 21 flowers, bracts reddish, pedicels ± pendent at anthesis, 4 - 10 (-15) mm.

Flowers : Calyx 4 - 7 mm, sepals appressed, triangular, acute 2 - 5 mm, petals oblong to oblong-oblanceolate, ventrally canaliculate, dorsally bluntly keeled, broadly acute,  9 - 16 x 2.5 - 3.5 mm, basally yellow or yellowish-green, apically red or strongly marked with red, glaucous, tube ± 3.5 - 5 mm, anthers reddish.

Cytology : n = 136

D. rigida has the highest chromosome number of any species of the genus. The species was lost for a long time but has been rediscovered by Moran (1987). Its relationships within Subgen. Dudleya are unresolved.