CHAPTER 13. CHARACTERIZATION OF SUBTRIBE ESPELETIINAE CUATRECASAS Espeletiinae Cuatrec., Phytologia 35: 48. 1976. Pachycaulous, perennial, and perennifoliate plants mostly with xerophytic structures. Trees, woody shrubs, and caulirosulas, monocarpic or polycarpic. Stems solidly woody or mostly with a broad central pith. Leaves usually more or less crowded at the distal ends of the stem or branches or many congested in sessile or stipitate rosettes (or caulirosulas). Leaves spirally arranged, the laminae rather large, entire (or minutely denticulate), rather oblong, pinnately veined, markedly xeromorphic, coriaceous or subcoriaceous, with areolar cavities, with hypodermis, and usually covered at least abaxially by dense indument. Foliar rays with compact files of procumbent cells. Synflorescences monotelic, either dichasial or monochasial, terminal or axillary, bearing capitula varying in number from 1 to a few hundred. Capitula heterogamous. Involucres pluriseriate; phyllaries subherbaceous or subchartaceous; outer ones sterile, 5-20(-50), ovate to oblong or linear, acute or obtuse, subequal or usually the external ones larger size and decreasing gradually inwards, abaxially more or less densely hairy; fertile phyllaries becoming less herbaceous inwards , indurate at base at maturity, embracing the achenes, at least distally hairy. Receptacle paleaceous, flat, convex, or conic, rarely semiglobose, glabrous or hirtulous; pales persistent, scarious or subscarious, embracing the flowers, distally barbate. Ray flowers female in 2-6 rows, ligulate, seldom eligulate; corolla tubes usually hairy; ligules basically white or yellow; style branches with 2 parallel, discrete, marginal, stigmatic lines. Disc flowers pseudohermaphroditic, functionally male, with rudimentary ovary; corollas pentamerous, tubular with the limb tubular, campanulate, or slightly infundibuliform, shortly lobed or dentate, hairy or glabrous, usually yellow; anthers shortly sagittate, endothecial cells oblong, nodular at the transverse walls, apical appendages ovate with a median keel and no glands; styles distally papillose-pilose with subapical crown of longer papillae, nonstigmatic, apex conical, emarginate, base immersed in a tubular nectary (sometimes called a disc). Achenes obovoid-pyramidal or oblong, sharply triangular to prismatic-quadrangular; apex rounded or truncate, base mostly acute or subacute, callose; abaxial side Âą convex, the other sides flat; surface
glabrous, smooth with no striations; cells of subepidermis with amorphous traces of a black pigment ("carbonized"); no pappus except for 3 sublanceolate squamellae in Tamania. . Schizogenous resiniferous ducts and cells distributed generally throughout the plant except in the woody tissue; the ducts usually occurring along the major veins of the leaves and corollas. Gland-tipped hairs particularly rich in tetracyclic diterpenoid compounds of the kauranoid molecular structures. Growth rings of the wood more or less marked or completely lacking, reflecting climatic oscillations in degree of dryness rather than seasonal periods. Tracheids present in arboreal species. Pore diameters larger in arboreal species (50-80 J.tm) than in rosulate species (28-61 J.tm). Vessel elements with simple vestigially bordered perforations, reticular unbordered perforations, and sometimes a few scalariform perforations with conspicuously bordered bars. Vessel lengths from 126-473 J.tm. Intervascular pitting mostly alternate, also scalariform and transitional, rarely opposite. Tyloses scarce, thin-walled, rarely abundant and with thick walls (Carramboa). Libriform fibers 2x longer than vessel elements, seldom septate. Woody uniseriate rays absent or scarce, multiseriate rays up to 10 cells wide. Ray cells usually 8- 90 x 10-25 J.tm in arboreal species, 90- 125 X 25-40 J.tm in caulirosulan species. Pollen grains tricolporate, spheroidal prolate to spheroidal oblate with 22- 42 J.tm polar diameter and 22- 38 J.tm equatorial diameter. Colpi usually narrow, rather shallow, with acute ends and finely granulate membrane. Germ pores well defined, rarely circular, usually elongate, rather constricted at the polar axis, and equatorial ends acute or rounded. Exine thinner between spines. Sexine thick. Tectum spiny, foraminate, baculate. Spines 1.5-7.0 J.tm long, conical, acute or obtuse, with an internal cavity near the base; perforations near the base in l-3 circles, larger at the spine bases than between them. Columellae thin, circular, appearing capitate in thin section, united at base into a more or less homogeneous membrane. Infratectum lacking, replaced by a continuous cavus, the nexine united to the sexine only at colpi. Nexine apparently homogeneous, sometimes slightly differentiated into nexine 1 and 2, the internal surface granular. Chromosome number n = 19. The features of the Espeletiinae described above separate them readily from other subtribes of the
ll3