Study on seed morphometry of some threatened Western Himalayan orchids

Abstract

Physical seed characteristics of 32 threatened Western Himalayan orchids belonging to 23 genera of 3 subfamilies were studied using light and scanning electron microscopy. The species showed remarkable seed shape variations (fusiform, spathulate, ovoid, filiform) irrespective of their taxonomic position. Epiphytes produced relatively small-sized seeds compared to their terrestrial, lithophytic, or mycoheterotrophic counterparts. Seeds were truncated (length/width < 6.0) in 27 species, and were mostly elongated (length/width = 19.957 ± 1.459) in the orchidoid species Goodyera biflora (Lindl.) Hook.f. The number or size of testa cells was found fairly consistent at the genus level, and their walls were straight, sinuous, or undulate. Periclinal walls possessed vertical or oblique ornamentation in 6 species, which is of taxonomic implication. Embryos were rather tiny and most of the seed space (even >90% in 7 species) was occupied by air. The highest seed to embryo volume ratio was recorded in terrestrial Liparis odorata (Willd.) Lindl. and the lowest in epiphytic Rhynchostylis retusa (L.) Blume, both of which are members of the advanced Epidendroideae. Seed characteristics are important in elucidating taxonomic, phylogenetic, and phytogeographic relationships among different orchid taxa.

The seeds micromorphology and morphometry of certain Dactylorhiza (Orchidaceae) species distributed in Turkey

“…As a result of the measurements and analyses in our study, the smallest cells were found in the species D. iberica and the species with the highest air space was found to be D. urvilleana. According to Verma et al (2014), Dactylorhiza hatagirea and some orchid seeds have more or less pentagonal and hexagonal cell shapes. The seeds we studied also yielded similar results and their cell shape was identified to be generally pentagonal.…”

Caracterización morfométrica de semillas de cuatro especies de orquídeas terrestres nativas de Argentina

“…Las semillas son una parte fundamental del ciclo de la planta y de su dispersión depende la supervivencia de la especie. Tanto su morfología como peso, composición y estructura influyen en la capacidad de dispersión y viabilidad (Verma et al, 2014).…”

“…De acuerdo a Arditti et al (1980) y Augustine et al (2001) la relación largo/ ancho (L/A) de semillas provee importante información en cuanto al grado de truncamiento de la semilla en orquídeas. Verma et al (2014) las clasifican en alargadas a las semillas que poseen una relación L/A mayor a 6,0 y truncadas a las menores a este valor. El grado de truncamiento puede ser usado para diferenciar especies entre los generos Aerides, Bulbuphyllum, Coelogyne, Cymbidium y Eria (Swamy et al, 2004).…”

“…Para el cálculo del volumen del embrión se los consideró como esferoides alargados, determinando su volumen con la fórmula 4/3 πab 2 , donde a = 0,5 longitud y b = 0,5 ancho. Semillas con relación Largo / Ancho (L/A) menores a 6,0 se clasificaron como truncadas y las mayores a 6,0 como elongadas, de acuerdo a Verma et al (2014). El porcentaje de aire de la semilla se obtuvo restando el volumen de la semilla al volumen del embrión y dividiendo este valor por el volumen de la semilla por 100 (Arditti, 1979).…”

Labellum micromorphology of some orchid genera (Orchidaceae) distributed in the Black Sea region in Turkey

“…The importance of micromorphological features for the taxonomic consideration of orchids has been investigated by several researchers (Lumaga et al, 2006;Verma et al, 2014). Aybeke (2012) examined anther wall development in Ophrys mammosa and emphasized that this finding was important in regard to taxonomical factors.…”