Waltheria bicolor J.G. Saunders

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Waltheria bicolor J.G. Saunders

Descripción

Heterostylous sprawling shrubs 1-1.5 m tall with clustered branches spreading from base, arching downward from tips; secondary branches, inflorescences and leaves distichous; all plant parts external to the petals stellate- tomentose with trichome radii 0.1-0.2 mm long, except where noted. Leafy stems quickly glabrescent; bark umber to grayish brown, dull. Leaves associated with the inflorescence abruptly reduced, lanceolate with obtuse bases, concolorous and canescent above and below; leaves not associated with the inflorescence discolorous, resinous and glabrate above; both types of leaf blades lanceolate to ovate, 1.8-15.0 cm long, 1.5-7.6 cm wide, acute at tip, rounded to cordate at base, with margins coarsely large and small dentate, revolute, with adaxial surface of leaves not associated with the inflorescence bright green and glabrate in age (reddish-brown when dry), with abaxial surface canescent, gray green (olive-green when dry); petioles 2.2-6.5 cm long, 0.5-1.0 mm wide, terete; stipules linear-triangular, 2.9-4.0 mm long, 0.2-0.5 mm wide. Inflorescences axillary, secund, cymose clusters to 3 cm long bearing 25-35 flowers, with branching pattern condensed but discernible; primary flowering unit consisting of 2 sessile flowers half-surrounded by 4 valvate bracts; 4 bracts fused at the base, but with the middle two fused for 0.7-2.0 (3.5) mm, bracts 3.8-5.0 mm long, 0.8-1.7 mm wide, with abaxial vein prominent, deciduous with fruit. Thrum flowers ca. 2-3 mm in diam., calyces 4.0-5.0 mm long; calyx tubes 2.2-3.1 mm long, 1.9-2.8 mm wide; calyx lobes 1.0-2.0 mm long, 0.9-1.1 mm wide; corollas yellow, petals eciliate, spatulate, 2.5-4.5 mm long, 1.1-1.4 mm wide, rounded or emarginate apically, glabrous; stamens 3.5-5.0 mm long; stamen tube 1.0-1.9 mm long; free filaments 1.5-2.8 mm long; anthers 0.9-1.3 mm long, 0.5 mm wide; pistil 2.5-3.2 mm long; ovary 0.7-1.2 mm long, 0.5-0.6 mm wide, sericeous above (radii to 0.5 mm long); style eccentric, 0.9-1.5 mm long, 0.2-0.3 mm wide, densely stellate-pubescent throughout (radii to 0.15 mm long); stigma oblong, 0.6-1.1 mm long, 0.3-0.5 mm wide, filiform, papillae to 0.6 mm long. Pin flowers similar except stamens 2.0-4.8 mm long, stamen tube 0.9-1.8 mm long, free filaments 0.7-3.0 mm long, pistil 5.4-5.7 mm long, ovary 0.6-0.7 mm wide, style 3.3-3.9 mm long, 0.1- 0.15 mm wide, densely stellate-pubescent on lower half, stigma 0.4-0.9 mm long, slightly angled, clavate papillose, with branches 0.1- 0.15 mm long. Fruit an ovoid capsule, 2.2-2.8 mm long, 1.6-1.9 mm wide, thin membranous, with partial loculicidal dehiscence. Seed reddish brown, 2.0-2.3 mm long, 1.4-1.5 mm wide, obconical with truncate-obtuse apex, with striate reticulate cells on cuticle, with testa glossy, smooth, dark chocolate brown.
Pollen. Thrum: spinose, apertures 5-6 (average 5.3 for N = 79), zonoporate, colpus index 7.7, 43.02 um x 50.70 Am wide, P/E = 0.85, spines 1.63 um long, 1.63 um in diam., ora 5.6 um long x 4.9 um wide (N = 30 for Koelz 34188, Saunders 1692 and 1748); pin: reticulate, apertures 5-6 (average 5.1 for N = 81), zonocolporate, colpus index 1.5, 34.0 um long x 38.2 ,um wide, P/E = 0.86, colpi 21.6 ,um long, 3.2 Am wide, lumen diam. 0.93 um, muri 0.93 um in diameter, ora 4.3 um long x 6.4 um wide (N = 29 for Saunders 1698, 1746 and Webster & Breckon 16120.).A

Forma de crecimiento

Arbusto

Forma de vida

Terrestre

Nutrición

Autotrófica

Distribución

México (país) EndémicoA

Elevación

250 – 500 mA

Tipo de vegetación

Selva bajaA

Categoría IUCN

No incluidaB

Categoría NOM-059-SEMARNAT-2010

No incluidaC

Estatus del taxón

(A) Como definida actualmente, probablemente una entidad natural (monofilética)

Bibliografía

A. Saunders J. G. 1993: Four New Distylous Species of Waltheria (Sterculiaceae) and a Key to the Mexican and Central American Species and Species Groups. Systematic Botany, 18, 2: 356-376
B. IUCN 2022: The IUCN Red List of Threatened Species. Versión 2022-2
C. SEMARNAT 2019: MODIFICACIÓN del Anexo Normativo III, Lista de especies en riesgo de la Norma Oficial Mexicana NOM-059-SEMARNAT-2010: 101 pp. – https://www.dof.gob.mx/nota_detalle.php?codigo=5578808&fecha=14/11/2019#gsc.tab=0 [accessed 2023-05-04 06:16]