Irlbachia

  • Authority

    Maguire, Bassett. 1978. The botany of the Guayana Highland--part XI. Mem. New York Bot. Gard. 32: 1-391.

  • Family

    Gentianaceae

  • Scientific Name

    Irlbachia

  • Description

    Genus Description - Dichasia axillary, more commonly terminal, symmetrical or often asymmetrical; flowers small; calyx tube shorter than the 5 imbricate lobes; corolla infundibuliform, often broadly so; stamens 5, filaments attached at the union of the tube and limb, anthers sagittate-lanceolate, at maturity strongly recurved; pollen in globular polyads, 150-200 µm diam, the grains beset with a circle of 3-5 flattish spines at the distal face (representing the Irlbachia-type of Nilsson); ovary 2-celled, ovules numerous, axillary, style commonly at length deciduous, stigma lamellate; capsule 2-valvate, dehiscing from the summit; seed very small, prismatic, alveolate. Low herbs, characteristically with 3-5-plinerved leaves; apparently restricted to Guayana and the middle Amazon and Rio Negro Basins.

  • Discussion

    7. Irlbachia Martius, Nov. Gen. Sp. 2: 201. Jan-Jul, 1827 (1826). Pagaea Grisebach, DC. Prodr. 9: 70. 1845. Brachycodon Progel, Mart. Fl. Bras. 6(1): 229. 1865. Type. Irlbachia elegans Martius. "In pratis silvaticis udiuscuhs prov. Alto Amazonas prope Ega oppidum, Martius.'' The genus, of some 10-12 species, with chief geographic concentration in Guayana, is held together by both consistent macromorphologic and micromorphologic characters. Most consistent and persuasive in this regard is the pollen morphology (Figs 80, 81, 83, 86, 87). Ten species are recorded here. The generic names Irlbachia, Mart., Pagaea Griseb., and Brachycodon Prog. may well indeed better fall in a single genus. There seems to be little macromorphologic evidence for maintaining them as distinct. The palynological evidence, as provided by Nilsson (1970), that Pagaea and Brachycodon are congeneric, seems to be sound. That Irlbachia, which has two (? or more) concentrically arranged spines on the distal pollen face, can be maintained as distinct from Pagaea and Brachycodon, which are purported to have a single distal polar circular arrangement of spines, is questionable. A critical review of the species based on all morphologic considerations would well resolve the problem.