A study of the reproductive biology of blue-flowered Conospermum species (Proteaceae)

Abstract

Blue-flowered Conospermum species are endemic to Western Australia, and are highly sought after in the horticulture industry. Aspects of the reproductive biology of several species were investigated. The paniculate inflorescences of Conospermum eatoniae E.Pritz. contain 6-10 florets; however, the uppermost two or three florets never open and only the basal one or two florets in an inflorescence set seed. When insect pollinators are excluded, flowers do not self-pollinate and set seed. Stigma receptivity occurred for up to 6 days following triggering of the style and was variable between C. eatoniae, C. amoenum Meisn. subsp. amoenum, C. caeruleum R.Br. and C. brownii Meisn. Hand-pollination with 10 pollen genotypes and two maternal C. eatoniae parents showed that although pollen tubes were observed in the style, no seed was set. Genetic analysis of open-set seed progeny showed that C. eatoniae outcrossed infrequently when grown in clonal rows in a plantation, but outcrossing was common in wild plants. This study demonstrates that the reproductive biology of blue-flowered Conospermum is complex and requires further investigation if the species are to be widely cultivated for horticulture.

Pollen adaptation to ant pollination: a case study from the Proteaceae

“…The flowers of Conospermum possess an active pollination mechanism. The style is bent, and the flower opens in a state of tension [ Stone et al , 2006 ; but see Douglas (1997) for a morphological description]. When a visiting insect applies pressure with its mouthparts at the base of the style it flicks away from the fertile anthers and strikes the visitor.…”

“…When a visiting insect applies pressure with its mouthparts at the base of the style it flicks away from the fertile anthers and strikes the visitor. The moist cup-shaped stigma is forced down onto the pollinator and thereby picks up pollen carried by the insect; at the same time the fertile anthers dehisce explosively, casting new pollen onto the visitor ( Morrison et al , 1994 ; Stone et al , 2006 ). Thus, Conospermum flowers need to be visited by insects carrying a suitable pollen load from previous floral visits in order for pollination to occur, leading to development of fruits.…”

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

“…There is a high degree of specialisation and speciation both in bees and the flowers they pollinate in the SWAFR (Figs 6-10). There are many native bees in WA that feed from plants in specific families or genera (oligolectic) and some specialise on a single plant species (Houston 1989(Houston , 2000(Houston , 2018Houston et al 1993;Wallace et al 2002;Stone et al 2006).…”

Isolation, characterization, and cross‐amplification of 20 microsatellite markers for Conospermum undulatum (Proteaceae)

“…Within the South West Australian Floristic Region, a global biodiversity hotspot (Myers et al., ; Hopper and Gioia, ), many Conospermum species are of increasing conservation concern, with four taxa already declared rare by the Western Australia government (Government Gazette, ). Moreover, as for many proteaceous species, various Conospermum species are widely utilized in floriculture (Bennett, ; Stone et al., ). Conospermum undulatum Lindl.…”

“…In Conospermum , studies of population genetics and reproductive biology have been undertaken using amplified fragment length polymorphism (AFLP) and random‐amplified polymorphic DNA (RAPD) markers for only a few species (Stone et al., ; Sinclair et al., ). To our knowledge, no microsatellite resources have been developed for this genus to date.…”