Studies on the ultrastructure of a three-spurred fumeauxiana form of Anacamptis pyramidalis

Agnieszka K Kowalkowska,Jerzy Bohdanowicz,Małgorzata Kozieradzka-Kiszkurno,Hanna B Margońska

doi:10.1007/s00606-012-0611-y

Agnieszka K Kowalkowska, Jerzy Bohdanowicz + Show 2 more

Open Access

https://doi.org/10.1007/s00606-012-0611-y

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Abstract

Floral spurs are regarded as features affecting pollinator behaviour. Anacamptis pyramidalis is regarded as a deceitful, non-rewarding orchid species. In the form fumeauxiana, additional spurs occur on the lateral sepals. In this study we analyse micromorphological and ultrastructural floral features and suggest the mechanism of deception in A. pyramidalis and A. pyramidalis f. fumeauxiana. In f. fumeauxiana, the adaxial surface of the lip, the lip calli, the tips of the lateral sepals, the abaxial and adaxial epidermises of the lip spur, and the lateral sepal spur have a secretory function. Numerous stomata were observed on the abaxial surfaces of spurs and sepals. The characteristic features of the ultrastructure of osmophore cells were noted: dense cytoplasm with numerous profiles of ER, mitochondria, plastids with plastoglobuli and tubular structures, a large nucleus, lipid droplets, and vesicles fusing with the plasmalemma. The similarity of the floral morphology and anatomy, the flowering period, and pollinators of A. pyramidalis, A. pyramidalis f. fumeauxiana and Gymnadenia conopsea suggest a possible food-deceptive mechanism—imitation of nectar presence produced in the spurs of Gymnadenia.

Highlights

Floral spurs are features affecting pollinator behaviour
Some remains of secreted substances on the adaxial lip surface were visible (Fig. 1c, d)
Scent may be produced by an undifferentiated epidermis, when the fragrances are emitted by diffusion (Mazurkiewicz 1913), or by osmophores—floral parts with glandular characteristics (Stern et al 1987; Vogel 1990; Wiemer et al 2008)

Summary

Introduction

Floral spurs are features affecting pollinator behaviour. Their important function of guiding pollinators to flowers is well known (van der Pijl and Dodson 1969; van der Cingel 1995). Approximately one third of orchid species are regarded as deceitful The presence of a spur, even if nectarless, noticeably increases the possibility of floral pollination in the orchids (e.g. Dactylorhiza majalis/Orchis latifolia) or in other species (van der Pijl and Dodson 1969; Nilsson 1988; Hodges and Arnold 1995)

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