Nectar trichome structure of aquatic bladderworts from the section Utricularia (Lentibulariaceae) with observation of flower visitors and pollinators

Abstract

In Utricularia, the flower spur is a nectary and in this organ, nectar is produced and stored. This study aimed to examine the structure of the nectary trichomes in four Utricularia species (Utricularia vulgaris L., U. australis R.Br., U. bremii Heer and U. foliosa L.) from the generic section Utricularia. We have investigated whether species with different spur morphology had similar spur anatomy and nectary trichome structure. In Utricularia flowers, nectar is produced by spur capitate trichomes (sessile or stalked). Our results showed that regardless of the various spur morphology, trichomes have similar architecture and ultrastructure. Head cells of these trichomes are transfer cells with an eccrine nectar secretion. Examined species differed in the micromorphology of papillae in spurs. The fly Eristalis tenax was found to be a pollinator of U. vulgaris. Small Halictidae bees seem to be pollinators of U. foliosa.

Systems analyses of key metabolic modules of floral and extrafloral nectaries of cotton

“…Our studies expand upon earlier descriptions of the morphology and ultrastructure of the cotton foliar nectaries (Eleftheriou and Hall, 1983a; Wergin et al, 1975), and extends such studies to the floral nectary and the reproductive extrafloral nectaries (i.e., bracteal and circumbracteal). The four nectaries of G. hirsutum share the basic structural components of similar trichomatic nectaries reported in other taxa ( Abutilon - Kronestedt et al, 1986; Hibiscus - Sawidis et al, 1987; Platanthera - Stpiczyńska et al, 2005; Utricularia - Plachno et al, 2018). Specifically, subnectariferous parenchyma is associated with vasculature.…”

“…In contrast to the previous studies of foliar nectaries, cell wall ingrowths were observed during the secretory stage of bracteal and circumbracteal nectaries on the distal cell wall of the papillae head cells. These ingrowths in the region of nectar secretion, may facilitate nectar secretion by increasing the surface area (Fahn, 1979; Plachno et al, 2018), which may be particularly important for the reproductive extrafloral nectaries that produce the largest volume of nectar and are active for the duration of fruit maturation (Wäckers and Bonifay, 2004).…”

“…During active nectar secretion, the cuticle of the papillae head cells separates from the cell wall and the newly formed subcuticular space, which fills with nectar; microchannels or fractures develop in the cuticle to facilitate the release of nectar from the nectary. This phenomenon commonly occurs in the trichomatic nectaries of a variety of other species, included within Malvaceae (Findlay et al, 1971b; Haratym and Weryszko-Chmielewska, 2017; Kowalkowska et al, 2018; Kronestedt et al, 1986; Lattar et al, 2018; Plachno et al, 2018; Sawidis et al, 1987). Based on previous observations of Abutilon hydridum floral nectary papillae, the cuticular channels may function as valves, releasing discrete droplets of nectar once hydrostatic pressure exceeds a threshold (Findlay et al, 1971b).…”

Flower nectar trichome structure of carnivorous plants from the genus butterworts Pinguicula L. (Lentibulariaceae)

“…The spur anatomy of the Pinguicula that were examined here is very similar to Utricularia (Płachno et al 2016(Płachno et al , 2017(Płachno et al , 2018(Płachno et al , 2019b. In both genera, there are collateral vascular bundles in the nectaries (spurs).…”

“…In Utricularia, the spur is treated as a nectary and nectar is produced by small glandular trichomes (Płachno et al 2017(Płachno et al , 2018(Płachno et al , 2019b. The ultrastructure of these trichomes was analysed by Płachno et al (2017Płachno et al ( , 2019c.…”