Chamaecrista serpens var. wrightii (A.Gray) H.S.Irwin & Barneby

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Authority

    Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 2: 455-918.

  • Family

    Caesalpiniaceae

  • Scientific Name

    Chamaecrista serpens var. wrightii (A.Gray) H.S.Irwin & Barneby

  • Type

    Holotypus, Wright 1034, GH! isotypi, K, NY, US!—Chamaecrista wrightii (Gray) Wooton & Standley, Contrib. U.S. Nat. Herb. 19: 335. 1915; Pennell, 1917, p. 342 (as comb. nov.).

  • Synonyms

    Cassia wrightii A.Gray, Chamaecrista wrightii (A.Gray) Wooton & Standl., Cassia palmeri S.Watson, Chamaecrista palmeri (S.Watson) Greene, Chamaecrista mazatlensis Rose, Chamaecrista ortegae Britton, Chamaecrista mexiae Britton, Chamaecrista chiapensis Britton & Rose, Cassia monserratensis Lundell, Chamaecrista alamosensis Britton & Rose

  • Description

    Variety Description - Stems mostly (1—) 1.5—4 dm, in desert environment weakly suffrutescent basally; vesture highly variable, the stems and petioles thinly incurved-pilosulous or thinly to very densely hispid with erect or subretrorse septate setae; larger lvs 2-3.5(-4) cm; petiole, (including pulvinus) 2-4 mm; gland l(-2, and rarely 1 or more on rachis), 0.2-0.5 mm diam, the stipe (0.2-)0.3-l mm; lfts of larger lvs (6—)7— 10(— 12) pairs, up to 5— 10(— 12) x 1.5—2.5(—3) mm, either olivaceous both sides or cinnamon-brown dorsally; fls large, the sepals up to 8— 12(—13.5) x 3-5.5 mm, the cucullus 13—19(—20) mm long; longer anthers 6-9.5 mm; style 6-10 mm; pod mostly 2.5-3.5(-4) mm, 6-ll(-12)-ovulate.—Collections: 53. [Key: "Fl larger, the asymmetric petal 9-19(-20) mm, the longer anthers to 4-9.5 mm, the style (4-)4.5-10 mm; discontinuously dispersed from s. Arizona to n. Argentina. Lfts of larger lvs 7-9(-12) pairs; Pacific slope of Sa. Madre Occidental from s. Arizona to Jalisco and e. through Sa. Madre del Sur to Guerrero; Chiapas. Fls large, the long petal 13-19(-20) mm, the long anthers to 6-9.5 mm, the style 6-10 mm; Arizona to Chiapas."]

    Distribution and Ecology - Dry hillsides, often in grassy places, extending from the coastal plain upward through short-tree forest into the pine-oak belt, 10-2100 m, locally plentiful along the Pacific slope of Sa. Madre Occidental from s. Arizona (Santa Cruz Co.) to centr. Jalisco and s.-e. locally and interruptedly to Sa. Madre del Sur in Guerrero, s.-w. México, and highland Chiapas, unknown as yet from Michoacán, Morelos, or Oaxaca.—Fl. (VI-)VII-I, exceptionally later.

  • Discussion

    Like var. serpens itself, the large-flowered var. wrightii varies greatly in density and proportions of the short incurved and long setose vesture and to considerable degree likewise, but independently, in the diameter of the petiolar gland and development of its stipe. The pubescence varies in a clinal mode, setae being absent or almost so (C. wrightii sens, str.) from Arizona south into Sinaloa (that is, within and around the periphery of the Sonoran Desert) and thence southward become increasingly long and many (C. palmeri sens, str.), culminating in a densely hirsutulous minor variant known from a few collections from s.-w. Durango (Rose 2253, 3482). Many collections of var. wrightii are characterized by a bright cinnamon-brown discoloration of the lower leaf-surface, but this sometimes appears erratically on only some leaves, or on only some plants of a population, and has no taxonomic value. Two of the three known collections from Sa. Madre del Sur differ slightly either in abnormally assurgent branches (Hinton 10536) or unusually many (-12) pairs of leaflets, but seem to represent no more than minor variants. The Chiapas populations, described by Britton & Rose as a species supposedly distinguished by the combination of strongly veined leaflets with submarginal costa, a short-stipitate gland, and relatively short pedicels, really do have prominently and closely venulose and narrow leaflets, but are otherwise matched at all points by distantly allopatric forms of var. wrightii. The types of Ch. alamosensis and Ch. mazatlensis were both collected in March, that is at the height of the dry season, and have lost their larger leaves in consequence; no structural differences from sympatric var. wrightii collected in the vigor of new growth can be detected. Despite the fact that Britton referred Ch. mexiae and Ch. palmeri to different groups, supposedly separable by leaf-texture, we can find no substantial difference between the types, collected at points in the río Santiago valley about 100 km apart in Jalisco and adjoining Nayarit respectively.

  • Distribution

    Arizona United States of America North America| Jalisco Mexico North America| Guerrero Mexico North America| México Mexico North America| Chiapas Mexico North America| Michoacán Mexico North America| Morelos Mexico North America| Oaxaca Mexico North America|