Pollen morphology of Rhododendron subgen. Tsutsusi and its systematic implications

Abstract

Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentanthera (G. Don) Pojarkova, respectively. Pollen morphology of all samples was observed using LM and SEM. Pollen grains are revealed to be spheroidal and tetrahedral with tricolporate apertures. Pollen sizes of subgen. Tsutsusi (Sweet) Pojarkova range from 37.67 μm to 61.06 μm, and the exine sculptures are more or less compactly granulated. Pollen sizes are significantly different between sect. Brachycalyx and sect. Tsutsusi of subgen. Tsutsusi. Rhododendron tashiroi Maxim. of sect. Tsusiopsis Sleumer shows a close affinity to sect. Brachycalyx. Pollen size and exine are consistent with general morphology in differentiating species in sect. Tsutsusi. Rhododendron huadingense B. Y. Ding & Y. Y. Fang, once placed as a member of sect. Brachycalyx, should be considered as a species in subgen. Pentanthera.

Pollen morphology of <i>Rhododendron</i> L. and related genera and its taxonomic significance

“…Thus they are found in M. pentandra, which has broadly urceolate (to campanulate) corollas, but not in other species of the genus with urceolate and/or tubular corollas. Gao et al (2002c); Zhang et al (2009) Usually, apocolpial exine is thicker than the septal exine, but thinner apocolpial exine has been observed in R. formosanum (Table 2). Similar relatively thinner apocolpial exine also has been observed in some taxa of the subfamily Vaccinioideae and it may have some taxonomic value in the infrageneric classification of the respected genera.…”

“…Pollen morphology has been shown to be useful for taxonomic and phylogenetic analysis of some Ericaceous taxa (Kron et al, 2002;Sarwar, 2007). The pollen of Rhododendron has also been studied by many researchers for taxonomic purpose as well as a part of regional flora (Huang, 1972;Vasanthy and Pocock, 1987;Fuhsiung et al, 1995;Mao et al, 2000;Terzioğlu et al, 2001;Gao et al, 2002b, c;Wang et al, 2006;Zhang et al, 2009;Miyoshi et al, 2011). All these results showed that pollen tetrads of Rhododendron were diverse in size and exine sculpture; sometime sufficient to differentiate the sections (Gao et al, 2002b;Zhang et al, 2009), but insufficient to differentiate the subgenera (Gao et al, 2002c;Wang et al, 2006).…”

“…Tsutsusi to subgen. Pentanthera has also been proposed based on palynological features (Zhang et al, 2009). In TEM, the pollen wall structure of R. tsusiophyllum especially the thickness of the columellae and the sexine-nexine ratio also showed a distinct difference (data not shown) compared to the two other taxa of Rhododendron (Fig.…”

Pollen Morphology of Ornamental Species in Asteraceae, Ericaceae, Fabaceae, Malpighiaceae, Malvaceae and Rubiaceae

“…Os autores descrevem ainda que a morfologia polínica é constante para o gênero, e que possui pouco valor diagnóstico para a distinção dos seus subgêneros como anteriormente sugerido (WANG et al 2006). Apesar disso em alguns casos é possível identificar espécies de Rhododendron pelos caracteres polínicos (ZHANG et al 2009 …”

COMPARISON OF POLLEN MORPHOLOGIES EXAMINATION OF SOME Rhododendron SPECIES - PLANT SOURCE OF MAD HONEY

“…Because of this characteristic of mad honey, the determination of the origin of toxic and non-toxic species in honey can provide an important tool in separating and packaging honey and preventing unwanted threats to human health. The pollen morphology of Rhododendron species is generally well studied (Yang et al, 2003;Wang et al, 2006;Zhang et al, 2009); however, there is limited information regarding the species from North-East Turkey. Milne et al (1999) investigated the hybridization between sympatric Rhododendron species distributed in Turkey at both the morphological and molecular levels.…”