This slide brings back memories of this fine plant I grew from a cutting I got from a friend years ago. This unusual white flowered form had been making the rounds and was supposed to have been originally collected by Ellaphie Ward Hilhorst, if memory serves me correct. She is the famous (among pelargonium lovers) artist who painted the superb illustrations in the Pelargoniums of Southern Africa book series. I had the pleasure of meeting her on my trip to South Africa in 1991, she was a most gracious lady.
Pelargonium cucullatum is the principal ancestor of the regal geraniums P. x domesticum. It is quite common around Cape Town, when I saw it in flower the bushes of it remind me of azaleas in effect. Typically the flowers are pinkish-purple, but as with most plants diligent searching sometimes reveals a mutant with a different flower color. There are three subspecies or variants of P. cucullatum, most easily distinguished by leaf shape and texture. This plant was from the ssp strigifolium form. I no longer have this plant, nor does the NYBG where I grew it years ago, though I think I have seed of it stashed somewhere in the fridge. Seed of P. cucullatum (and other pelargonium species within section Pelargonium of the genus) is very long lived, even if stored at room temperature seeds can still be viable more than a decade later. Depending on the genetics of flower color in this species, if I could find the seed I might be able to grow out a similar plant, or perhaps they would come out more typically colored. In any case, it is hard to flower P. cucullatum without a greenhouse or cold sunroom, since it needs cool nights, preferably with short days, to set flower buds.