Floral nectary morphology and evolution inPedicularis(Orobanchaceae)

Abstract

Intricate associations between floral morphology and pollinator foraging behaviour are common. In this context, the presence and form of floral nectaries can play a crucial role in driving floral evolution and diversity in flowering plants. However, the reconstruction of the ancestral state of nectary form is often hampered by a lack of anatomical studies and well-resolved phylogenetic trees. Here, we studied 39 differentially pollinated Pedicularis spp., a genus with pronounced interspecific variation in colour, shape and size of the corolla. Anatomical and scanning electron microscopy observations revealed two nectary forms [bulged (N = 27) or elongated (N = 5)] or the absence of nectaries (N = 7). In a phylogenetic context, our data suggest that: (1) the bulged nectary should be the ancestral state; (2) nectaries were independently lost in some beaked species; and (3) elongated nectaries evolved independently in some clades of beakless species. Phylogenetic path analysis showed that nectary presence is indirectly correlated with beak length/pollinator behaviour through an intermediate factor, nectar production. No significant correlation was found between nectary type and nectar production, beak length or pollinator behaviour. Some beaked species had nectary structures, although they did not produce nectar. The nectary in beaked species may be a vestigial structure retained during a recent rapid radiation of Pedicularis, especially in the HimalayaHengduan Mountains of south-western China.

Taxonomic traits in the microstructure of flowers of parasitic Orobanche picridis with particular emphasis on secretory structures

“…O. picridis has gynoecial nectaries located at the base of the elipsoid ovary forming an asymmetrical yellow gland with varied thickness and height. A similar location and colour of nectaries in other representatives of the family Orobanchaceae has been described by Bekker and Kwak (2005), Pujadas-Salvá (2010), and Liu et al (2015). In turn, similar to O. picridis, an ellipsoid shape of the ovary was observed in O. owerinii, O. minor, O. reticulate, and O. armena (Zare et al 2014;El Mokni et al 2015;Sardar 2019).…”

Enhanced reproductive success revealed key strategy for persistence of devastated populations in Himalayan food‐deceptive orchid, Dactylorhiza hatagirea

“…; Liu et al . ), although there was a dearth of information in the literature relating to a few species. Such species were assigned rewarding status only when most of other species in the respective genus were reported to have pollinator rewards (Baz ; Jiarui et al .…”

“…The species resembling D. hatagirea were then selected, using the literature, for their rewarding nature (whether they provide nectar, pollen, etc., to pollinating insects). Most of the coblooming species observed were found to be nectar rewarding (Duffy & Stout 2008;Dauber et al 2010;Thakur & Bhardwaj 2011;Saini et al 2012;Liu et al 2015), although there was a dearth of information in the literature relating to a few species. Such species were assigned rewarding status only when most of other species in the respective genus were reported to have pollinator rewards (Baz 2002;Jiarui et al 2007;Saini et al 2012;Guo 2015;Janšta et al 2015).…”

Nectarless flowers with deep corolla tubes inPedicularis: does long pistil length provide an arena for male competition?

“…Evolution of the deep corolla tube cannot be directly selected by long‐proboscid pollinators because louseworts with deep corolla tubes do not produce nectar although at least some long‐tubed Pedicularis spp. do have a rudimentary nectary structure (Liu et al ., ) and are exclusively pollinated by pollen‐collecting bumble bees (Macior & Sood, ; Macior & Tang, ; Yang et al ., ; Ree, ; Huang & Fenster, ; Eaton et al ., ). Because most long‐tubed louseworts are rosette plants or have lax stems that bear flowers close to the ground, a long corolla tube was suggested to function in elevating the corolla away from vegetative parts obstructing pollinator attraction (Macior & Sood, ; Macior & Tang, ; Huang & Fenster, ).…”