Psorothamnus emoryi var. arenarius (Brandegee) Barneby

Authors

Rupert C. Barneby

Authority

Barneby, Rupert C. 1977. Daleae Imagines, an illustrated revision of Errazurizia Philippi, Psorothamnus Rydberg, Marine Liebmann, and Dalea Lucanus emen. Barneby, including all species of Leguminosae tribe Amorpheae Borissova ever referred to Dalea. Mem. New York Bot. Gard. 27: 1-892.

Family

Fabaceae

Scientific Name

Psorothamnus emoryi var. arenarius (Brandegee) Barneby

Type

based on Dalea tinctoria var. arenaria (sandy, of the habitat) Brandg. Proc. Calif. Acad. Sci. II, 2: 147. 1889. — "Sands of the sea-shore, Boca de Soledad [s.-e. of La Paz]." — Holotypus, collected Jan 28, 1889, UC! — Psorothamnus arenarius (Brandg.) Ryd

Synonyms

Dalea tinctoria var. arenaria Brandegee, Psorothamnus arenarius (Brandegee) Rydb., Parosela arenaria (Brandegee) Standl., Parosela emoryi var. arenaria (Brandegee) I.M.Johnst., Dalea tinctoria Brandegee, Psorothamnus tinctorius (Brandegee) Rydb., Parosela tinctoria (Brandegee) Standl., Psorothamnus dentatus Rydb., Parosela dentata (Rydb.) Standl.

Description

Species Description - Frutescent in age but flowering as a herb, sometimes in its first year of growth, varying from densely white-tomentulose to thinly gray-tomentulose or almost glabrous up to the inflorescence; stems densely verruculose with prominent orange glands, many of them emergent above the tomentulose vesture; terminal leaflet mostly 1-2.5 (3.5) cm long, rarely only 0.5-1 cm; spikes either capitate or becoming oblong-cylindroid, 7.5-10 mm diam at anthesis, the axis (3) 5-20 mm long; calyx as described in key, the glands on tube mostly fewer than in var. emoryi, 3-6 in 1 row; keel ± 5.7-6.7 mm long, the obovate blades 3.7-4.6 mm long, 2.4-2.9 mm wide, proportionately broader than in var. emoryi; androecium 5.7-7 mm long; n = 10 (Spellenberg, 1973).—Collections: 47 (o).

Distribution and Ecology - Dunes both maritime and interior, sandy washes, occasionally on rocky hillsides, mostly below 300, rarely up to 400 m (1200 ft), common and locally abundant, in places forming open thickets, deserts of Baja California Sur northward on both coasts from the latitude of Bahia La Paz, especially abundant on sandy plains of Viscaino Desert, e. to the Gulf islands (Islas San Francisco, San Jose, Catalina, Monserrate, and Tortuga), and extending feebly n. of the boundary at 28° N into extreme s. Baja California Norte, at its n. limit intergradient to var. emoryi. — Flowering both in spring and summer, following rains, occasional in fall and winter.

Discussion

(Plate V)

The var. arenaria as known to Brandegee is a subherbaceous, thinly pubescent, mostly maritime phase of Ps. emoryi in which the flower-spike tends to become oblong-cylindroid rather than globose in age. Its short, almost symmetrically campanulate calyx and violet- margined petals, however, are found also on shrubby plants with aspect and habit of var. emoryi as this occurs in the Colorado Desert far northward. Plants of the latter type, that is with the habit of var. emoryi but a modified flower, correspond with D. tinctoria sens. str. Wiggins (1940, p. 48-49) has pointed out that these two forms have a common and almost equally extensive range in Baja California, and they appear to be artificial segregates, possibly reflecting seasonal rather than genetic variation.

Some specimens from the Gulf islands are in one way or another intermediate between var. emoryi and var. arenarius. As far south as Isla Catalina Moran collected an individual variant (No. 9328) which has the violet petals and relatively broad and short-toothed calyx of var. arenarius, but the calyx-tube is abnormally long (3 mm) for the latter and the ventral pair of teeth is partially united behind the banner as in var. emoryi. At Kino Bay in coastal Sonora facing Tiburon Island an often sampled population of Ps. emoryi has with the pink-purple petal coloring of var. emoryi a small calyx approaching that of var. arenarius. The whole range of Ps. emoryi extends north and south about 1400 km. While there is much evidence that genetic drift is operating toward the segregation of northern and southern entities, this separation has not yet reached the point of establishing discrete species.

Distribution

Mexico North America| Baja California Mexico North America|