Diversity of labellar micromorphological structures in selected species of Malaxidinae (Orchidales)

Agnieszka Kowalkowska,Hanna B Margońska

doi:10.5586/asbp.2009.019

Abstract

There are no papers examining the labellar micromorphology in Malaxidinae in detail. The aim of this paper is to present the results of labellar micromorphology of our studies on Malaxidinae. The micromorphology of nine species was examined and described (calli, nectaries, OP structures, concavities). These species are divided into six groups of which the lip morphology probably represents different forms of attracting and rewarding pollinators. Group one consists of Disticholiparis gregaria and Platystyliparis aurita with characteristic globular nectary and pad-like callus. The second group with Liparis nervosa has two conelike convexities. The third one is represented by Liparis sutupensis with spread lip, the basal callus, and the epichile often eroding with age. The fourth group (Stichorkis cespitosum) has a massive hypochil with basal callus and delicate epichil. The fifth group (Microstylis ophioglossoides, Dienia ophrydis) is characterized by a lip with developed lateral lobes, three deep concavities in the middle part, an erect callus, and many raphide cells.Crepidium cf. rheedii and Crepidium dryadum from the sixth group have a three-lobed lip with entire or toothed mid-lobe, basal callus, cavity surrounded by a rim and OP structures with raphide cells. We also emphasized the different way and place of nectar secretion in the subtribe and gave some suggestions about pollination strategies.

Highlights

Plants create a lot of structures and mechanisms to attract and reward pollinators
In descriptions of different pollination strategies it is reported that the flowers teasers as colour and scent play at first a major role and rewards are in the second place (Proctor et al 1996)
More complex strategies like pseudocopulation and pseudoantagonism are well-known in Orchidales

Summary

Introduction

In descriptions of different pollination strategies it is reported that the flowers teasers as colour and scent play at first a major role and rewards are in the second place (Proctor et al 1996). In Orchidales rewards as nectar, pollen, pseudopollen, oil and wax enhance pollinators to visit the flower. More complex strategies like pseudocopulation and pseudoantagonism are well-known in Orchidales (van der Pijl and Dodson 1969). The major orchid attractant is nectar (van der Pijl and Dodson 1969; Arditti 1992; Dressler 1993). The term nectary itself suggests where it is produced and offered being visible for pollinators, but does not imply the same origins and positions for all types of nectaries (Pacini et al 2003). More specialized orchids form a spur developing from tepals (van der Pijl and Dodson 1969). The secretory cells of the nectary by which the nectar is exuded may be ordinary epidermal cells, trichomes or nectariferous parenchyma cells where nectar is transported into specialized intercellular spaces and outside through stomata (Fahn 1979, 1988a, b)

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