Xanthorrhoea (genus)

• Add to collection

This is a very interesting sighting. The leaves appear too lax (arching over) to be X. resinosa, which typically exhibits tough leaves that radiate from the crown in an upright tuft relatively straight with little flexion. X. resinosa also usually produces single caudex, this has multiple crowns, more like that of X. concava, however the leaves seen very narrow for this species. It looks more like X. fulva, however this species does not occur this far south in NSW. This may be a narrow-leaved form of X. concava or perhaps an unreported hybrid between X. concava x australis.

Hybridisation in Xanthorrhoea does indeed occur, and is likely to be widespread where different species converge, however it does not appear to occur as extensively as is believed, this is because it can only transpire under very particular environmental conditions, such as where two species have overlapping geographical distributions alongside a coincidental flowering period in conjunction with where they meet across a transitional zone comprised of a gradual environmental gradient. i.e. areas bounded by two ecosystems or an ecocline, for instance a region between clay and sandy soils or wet and dry habitats. Fundamentally these are always environments comprised of conditions not preferred by either parent.
Morphological intergradation can also occur when two or perhaps more species are found within close proximity of each other, and populations displaying intermediate characteristics between species may be interpreted as hybridisation but may be the result of lateral gene transfer, which is the transfer of genetic material between two organisms. Molecular and genetical analysis could prove the best means with which to resolve the taxonomic problems associated with this genus.