Pelargonium betulinum pale flower

The petals of Pelargonium betulinum in picture are not always white as seen here. Petal markings, size and shape, as well as other plant features tend to vary. Collectively all these features remain the key to plant identification, by retaining that distinctive cluster of attributes that bring recognition and allow continuation of the species. Symbiotic relations with other species constitute a reason why species need to be recognised by service providing "foreign" neighbours, those that are very different but have long-standing relationships. Science ascertains species identity today by inspecting the DNA. 

Older species may have expanded and compounded the range of their individual differences and similarities, both justifying the recognition of forms, variations, subspecies as related and eventually splitting of species within the genus. Such differences multiply over time from responding evolutionary to more challenges, especially where large distribution ranges apply. Speciation characterises all living things that perpetuate themselves through offspring amidst environmental challenges to survival, in very gradual, small steps over may generations. 

The complexity of life forms can also be glimpsed within the individual specimen. The allure of plant flowers being a special case of this phenomenon. Note for instance how colour and form of the petal markings change here between the base and higher up on the upper petal pair. It is pink lower down with straight lines, dark purple with branched and angled lines higher up.

The sepals around the corolla tube are narrow and hairy, attenuating to sharp tips. Not all plant attributes are up for transformation by evolution at one time, depending on the nature of the particular environmental changes that have to be responded to.