Dalea compacta var. compacta

  • Title

    Dalea compacta var. compacta

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Dalea compacta Spreng. var. compacta

  • Description

    47a.  Dalea compacta Sprengel var. compacta

    (Plate LVIII)

    Stems commonly decumbent; leaflets often 3+ mm wide; otherwise as given in key. — Collections: 16 (i).

    Calcareous or chalky prairies, s.-ward on chernozem soils of the Coastal Plain, local, Red River valley in s.-e. Oklahoma, downstream from Bryan County, and adjoining Texas and Arkansas; disjunctly on the Coastal Plain of s.-e. Texas; cf. Wemple, 1970, map 14, as Petalostemon decumbens. — Flowering April to June. — Representative: Oklahoma: Waterfall 12,427 (OKLA, UC, WIS); Stevens 3639 (NY); Ripley & Barneby 7427 (NY); Wemple & Jackson 579 (NY). Arkansas: Moore & Iltis 442, 5159 (WIS). Texas: Wemple & Jackson 731 (NY).

    Dalea compacta (dense, of the spike) Sprengel, Syst. 3: 327. 1826. — "Ad fl. Rio Roxo in ditione Arkansa Amer. bor. " — Holotypus not known to survive, but presumed to be an isotypus of Petalostemon decumbens Nutt. — Petalostemon compactus (Spreng.) Swezey in Doane, Coll. Nat. Hist. Stud. 1 (Neb. Fl. Pl.): 6. 1891, exclus. syn. & pl. cit. Kuhniastera compacta (Spreng.) O. Kze., Rev. Gen. 192. 1891, exclus. syn.

    Petalostemon decumbens (lying down, of the stems) Nuttall, Jour. Acad. Philad. 7: 93. 1834.— "On the plains of Red river, common." — Lectoholotypus (Wemple, 1970, p. 84, 86), collected by Thomas Nuttall near Fort Towson, in present Choctaw County, Oklahoma, in May, 1819, NY! isotypi, GH, K (herb. Benth., herb. Hook.), P!—Kuhniastera decumbens (Nutt.) O. Kze., Rev. Gen. 192. 1891.

    The var. compacta is poorly differentiated from the widespread var. pubescens by the combination of shortly stalked flower-spike and elongate bracts projecting beyond the calyces. In addition the stems are more often diffuse than those of var. pubescens, and the leaflets of primary leaves are often broader; but the individual flowers are identical: My concept of var. compacta coincides exactly with Petalostemon decumbens of Wemple (1970, p. 84, fig. lib), who remarks on the curious bicentric distribution, with a gap of 200 miles separating the populations on Red River and those in southeastern Texas. This difficulty largely disappears if var. compacta is reinterpreted as an eastern variant of var. pubescens (= Petalostemon pulcherrimum of Wemple’s revision), the collective range of the species, sens, lat., here called Dalea compacta, being then continuous across the eastern half of Texas, with var. compacta emerging around two peripheral segments.

    The epithet compacta is taken up, following Shinners (1949, p. 83) for Petalostemon decumbens in the belief that Sprengel could have received plants from Red River in what was then called "Arkansa" (including much of present Oklahoma), before 1826, only from Nuttall. Nuttall is known to have sent Sprengel a set of his Arkansas collections of 1819, among them material of Dalea lanuginosa Nutt, which Sprengel renamed D. lanata. Sprengel’s disregard for Nuttall’s manuscript names led to a historic quarrel, so we should not be surprised to find in the case of Petalostemon decumbens a similar change of epithet. The locality given for Sprengel’s two Dalea is the same, just as the locality given by Nuttall for his D. lanuginosa and P. decumbens are the same. Not only does the circumstantial evidence point strongly to the identity of D. compacta and P. decumbens, but the species to which the epithet compacta has been applied in recent years (see discussion of D. cylindriceps) lies beyond the limit attained by botanical exploration at the period when Sprengel was composing his Systema.