Friday, March 20, 2015

Lenten Rose

These are three different winter roses or Helleborus x hybridus. They are the same genus as H. foetidus and therefore members of the buttercup family, Ranunculaceae. The colourful flower parts are not petals but sepals. The former have evolved into nectar-holding structures. Sepals tend to persist after petals are lost, consequently these remain colourful for a long time. They are also evergreen, hardy, winter-flowering and shade tolerant, hence their popularity amongst gardening folk.
It's probably time to grasp the differences between hybrids and infra-specific classification in more detail. I've already mentioned sub-species (denoted ssp.) but there can also be hybrids, varieties and forms.
Hybrids can be biological or taxonomic. Usually I think of them in the latter way: Hybrids are crosses between two different subspecies in the same species (intraspecific); two different species in the same genus (interspecific); two species from different genera (intergeneric) and, very rarely, two species from different families (interfamilial). In this case H. orientalis and its subsepecies or closely related species such as H. purpurascens or H. niger.
Varieties tend to be geographically separate 'versions' of the same botanical species. If different varieties of the same species are brought together they can breed. 
Form is below variety and some consider it a pointless division as it merely reflects genetic variation: e.g. a plant with commonly purple flowers might occasionally produce white forms, usually denoted as Genus species f. alba. In zoology it has no taxonomic validity.
A cultivar (cultivated variety) is a plant with particular characteristics which can be perpetuated by propagation and are selected, usually, by human intervention. All food plants grown commercially are cultivars. e.g. Solanum tuberosum 'King Edward'. 

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