Barbacenia irwiniana L. B. Sm.

Barbacenia irwiniana L. B. Smith

SPECIMENS EXAMINED.—Porto 1140.

SURFACE VIEW.—Hairs: few fingerlike projections present on abaxial surface. Epidermis: adaxial cells square to rectangular; abaxial cells square to rectangular; cells thin walled. Stomata: paracytic, 15 × 6 μm; present on abaxial surface.

TRANSVERSE SECTION OF LAMINA.—Dorsiventral; V-shaped with small median adaxial groove; margins of lamina turned inversely. Adaxial surface slightly undulating; abaxial surface with very small furrows. Epidermis: adaxial cells rounded to rectangular in shape; abaxial cells mainly dome shaped; cells on both surfaces thin walled. Subjacent to adaxial epidermis is a single layer of parenchyma cells. Cuticle: very thick and slightly ridged on adaxial surface; thin and slightly ridged on abaxial surface. Stomata: present in abaxial furrows; no substomatal chamber observed. Mesophyll: two to three layers palisade cells grading into loosely arranged spongy tissue. Few translucent cells in spongy tissue. Vascular bundles: 39; few commissural bundles observed. Usually one large vessel present in each vascular bundle. Two phloem units laterally arranged in flanges of Y-shaped abaxial girder. Adaxial girder present on each vascular bundle. Each vascular bundle completely surrounded by a bundle sheath. Crystals and tannins: none observed.

Barbacenia irwiniana L. B. Smith

Barbacenia irwiniana L. B. Smith, Contr. U.S. Nat. Herb., 35:276, pl. 10: figs. 17, 18, 1962.—Ayensu, Smithsonian Contr. Bot., 15:55, pl. 48a, 1974.

TYPE.—In narrow crevice among rocks on steep slope, Pico da Bandeira, Serra Caparao, Minas Gerais, Brazil, 2700 m alt, 3 March 1959, Irwin 2803 (US, holotype; NY, isotype).

DISTRIBUTION.—Known only from the type-locality.