For the final time as a work-learn student with BPotD, Bryant DeRoy is again the author of today’s entry. He writes:
A big thank you to Robert Klips (aka Orthotrichum@Flickr), who is a regular Botany Photo of the Day contributor via the BPotD Flickr Pool. Today’s image is of Ptilidium pulcherrimum, one of three species in its genus and the only genus in its family, the Ptilidiaceae. This is the final post in the series on liverworts, and sadly, the last post in my one-year stint as BPotD work-learn assistant. I’d like to thank all of those who supported my position with their generous donations. (Daniel adds: I agree — I especially appreciate that the sustained generosity means it’s rare I have to mention it, and we can all instead keep focused on the plants. I expect to be introducing a new student assistant next week for the summer.)
Species of Ptilidium are mostly distributed around northern temperate regions of the world, but populations of Ptilidium ciliare are known from at least New Zealand and Tierra del Fuego in the Southern Hemisphere. This led to a hypothesis that the lineage evolved in Gondwana with a subsequent single dispersal to the Northern Hemisphere (and then evolution of the other taxa). However, recent molecular studies more strongly suggest that Ptilidium ciliare spread to its disjunct southern occurrences via separate long-distance dispersals from the north, by the translocation of plant fragments.
Like the other members of its genus, Ptilidium pulcherrimum is dioecious and thus produces antheridia on male plants and archegonia on female plants. Fertile individuals are common among Ptilidium pulcherrimum, and they tend to produce sporophytes or capsules. The genus name stems from the Greek word Ptilidion, meaning “small feather”, alluding to the feathery appearance of the leaves. Densely packed marginal cilia on the deeply lobed leaves is cause for the billowy appearance of Ptilidium pulcherrimum. The leaves are generally around 1.8mm wide and roughly 1.4mm long. It can typically be found on living trees and woody shrubs, and can appear reddish to yellowy-green from afar.