Pollen release in the Proteaceae

Pollination strategies are exceptionally complex in southwestern Australia – a globally significant ancient biodiversity hotspot

“…For PGL these include detailed studies of pollination especially concerning buzz pollination and pollen presentation in the Ericaceae, Malvaceae, Proteaceae, Myrtaceae and Thysanotus (e.g. Ladd 1994;Ladd et al 1999;Ladd and Bowen 2020). We also provide >3000 supplemental images and 40 videos supporting pollination syndrome allocations (Table 3).…”

“…For example, the stigma of S. latifolia (the only specifically wind-pollinated Australian Proteaceae) is enlarged (Fig. 2v-x) compared with those of its sister species, and pollen is explosively released (Ladd and Bowen 2020). Wind-pollinated species tend to be dioecious (Table 4).…”

“…Pollinator switches between birds and insects has occurred in the sister genera Grevillea and Hakea (see Table S1). Mast et al (2012) proposed that in Hakea bird pollination was the ancestral system, but later phylogenetic studies found insect pollination may have been earlier (Mast et al 2015;Ladd and Bowen 2020). Non-flying mammal pollination, especially by honey possums, is observed or strongly suspected in at least 33 taxa in Banksia, and a few 52 in Grevillea (Table S1).…”

“…The Proteaceae in Australia has developed unique insect pollination syndromes, especially due to pollen release complexity (Carolin 1961;Holm 1988;Bernhardt et al 2019;Ladd and Bowen 2020). Banksias have an open floral morphology that attracts insects, birds and mammals, and many are primarily pollinated by birds and mammals where the combination of a stiff style and plastic stylar tip only allows pollen from large pollinators to be inserted into a pollination chamber (Ladd et al 1996;Thavornkanlapachai et al 2019;Ladd and Bowen 2020). Secondary pollen presentation, which may have evolved as a response to larger vertebrate pollinators, occurs locally in 11 genera and 750 taxa (see Ladd and Bowen 2020, Table 4).…”

“…Delnevo et al (2020b) found honeybees were ineffective for pollination of Conospermum undulatum, which requires a specific native bee to trigger its anthers. There is also one species (S. latifolia) with wind pollination (see Wind), whereas others in this genus are insect pollinated with explosive pollen release (Ladd and Wooller 1997;Ladd and Bowen 2020) and are primarily visited by bees (Houston 2000). Relatively specific pollination by bees (Fig.…”