Chamaecrista glandulosa

  • Title

    Chamaecrista glandulosa

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Chamaecrista glandulosa (L.) Greene

  • Description

    47. Chamaecrista glandulosa (Linnaeus) Greene, Pittonia 4: 286. 1899, sens. magnopere ampliat. Cassia glandulosa Linnaeus, Syst. Nat. ed. 10, 1017. 1759 —Typus infra sub var. glandulosa indicatur.

    Perennial, either potentially frutescent or arborescent (even though precociously flowering the first season as soft-stemmed herbs) or truly herbaceous but the stems then arising from the crown of a pluricipital and vertical (never rhizomelike) lignescent root; lfts of larger lvs (8-)9-24 pairs (sometimes slightly fewer in rare Andean vars. andreana, andicola and balsasana and in Mexican var. parralensis, but these at once emphatically perennial or fruticose and large-fld), the midrib centric or moderately (in var. tristicula strongly) displaced; peduncles at least shortly adnate to stem; pedicels 7-31 (-50) mm, the longer ones nearly always at least 10 mm, at least in fruit; fls mostly large or of moderate size, the long abaxial petal (8-)8.5-19(-23) mm; style linear (3-)3.4-8.7 mm (but sometimes abortive and shorter in some individual fls). Habit, pubescence, petiolar glands and venulation of lfts highly variable, described separately for each variety.— Centr. and s. Mexico and West Indies; Orinoco Valley in Venezuela; Andes from n.-w. Venezuela and n. Colombia to s. Peru and Bolivia; s.-e. Brazil; naturalized and cultivated elsewhere.—Fig. 2 (petiolar nectary).

    The foregoing description of Ch. glandulosa is formulated in general terms such as to cover all but three of the perennial or fruticose Neotropical chamaecristas in which supra-axillary pedicels coincide with relatively large, long-pedicelled, dolichostylous flowers and scarcely or (except in var. tristicula) moderately asymmetric leaflets with midribs varying from centric to displaced by about one third of the blade’s breadth. The exceptions noted are Ch. deeringiana of southeastern United States, distinguished by its unique horizontal root-system, the local Andean Ch. pedemontana and polymorphic West Indian Ch. lineata each different from sympatric forms of Ch. glandulosa in the relatively few leaflets. The species as here interpreted is precariously distinguished from extra- tropical Ch. fasciculata by the perennial life-span, and the more precariously and artificially so because many of its forms flower in their first year from soft essentially herbaceous stems, while races of Ch. fasciculata native to frostless peninsular Florida may survive the winter to become bushy-branched and basally lignescent. Duration of the root is again the only deciding difference between Ch. glandulosa sens. lat. and Ch. nictitans sens. lat., but all of the latter except its subsp. disadena are distinguished further by smaller or shorter-pedicellate flowers. Leaflets with strongly displaced or marginal midrib furnish the only ultimately diagnostic character of the group of Ch. rufa, Ch. chamaecristoides and Ch. pedicellaris, and this difference is blurred by Ch. glandulosa var. tristicula, which we find inseparable from var. flavicoma except in this one feature. As here defined, Ch. glandulosa is coextensive, if taxa discovered after 1871 are disregarded, with Bentham s Cc. flavicoma, glandulosa, virgata, and chamaecrista var. brasiliensis combined. Bentham separated the first three primarily on characters of pubescence now found to have very little biological significance or taxonomic utility; he seems to have associated var. brasiliensis with North American Ch. fasciculata under the misapprehension that it was herbaceous. In the light of material gathered since Bentham’s revision the discontinuities sundering Ch. glandulosa from the larger-flowered races of Ch. nictitans subsp. disadena on the one hand and from Ch. fasciculata on the other, have become so nebulous and moreover so unsatisfactory theoretically, that a return to Otto Kuntze’s concept of an all-embracing Cassia chamaecrista, at least as this applies to the genuine Chamaecristae of the New World, must appear very attractive. The price, however, is an elaborately cumbrous taxonomic hierarchy even more forbidding and difficult to use than that proposed in this revision.

    Due to the basic instability of those few phenetic characters which we have found helpful or diagnostic in defining geographically acceptable races within Ch. glandulosa, a key to its component varieties is extraordinarily difficult to construct, indeed is probably unattainable in the dependable form that one would wish. This reflects, of course, the contemporary stage of evolutionary activity and racial immaturity everywhere visible in the supra-axillary chamaecristas. While disapproving any key based primarily on dispersal patterns rather than morphology, we have been reduced to the expedient of two varietal keys, one for the endemic West Indian varieties of Ch. glandulosa, the other for its continental ones.