“Black” flowers - very desirable to many gardeners, even though (strictly speaking) they are not a true black. Rather, the black colour is due to a composite of dark coloured pigments in high concentrations. Despite a truly black flower being unattainable, plant breeders and hybridizers on occasion do their best to produce the darkest flower possible, and so flowers which are bred to be black are not impossible to find in the marketplace.
There are, however, a few plants that haven't been bred to be black, bur rather evolved that way. Salvia discolor (Andean silver-leaf sage) is one of those few. I was hoping to tell the story of why Andean silver-leaf sage has black flowers, but came up with very little while researching the evolutionary biology of its flower colour. Is the pigmentation irrelevant to its pollinators? If that's the case, why undergo the biological cost of concentrated pigmentation? Is the colour a strategy to accelerate floral development by increasing heat absorption (keeping in mind that it grows in high altitudes in the Andes) and thus biological activity? I'm speculating quite a bit; I don't have any expertise with floral pigmentation and development, but maybe someone with knowledge will comment and provide some answers (or at least more informed speculation!).
I should mention that if you live in the Vancouver area, you can pick up this plant at UBC Botanical Garden's Perennial Plant Sale on Sunday - first come, first serve though, and I suspect Salvia discolor will sell out quickly. One of the great things about the sale (for you) is that the public get first dibs - volunteers and garden staff have to wait an hour after the sale opens to purchase plants. Good for you, not so good for me - but I don't have a sunny spot at home to grow it anyway, as much as I like the plant.
A couple of other housekeeping notes: David Winter at Science and sensibility added the Botany Photo of the Day and the UBC Botanical Garden Weblog to his list of weblogs devoted to botany: Botany in the Blogosphere (after I had commented on his original list). David particularly liked the tagline “In science, beauty. In beauty, science. Daily.”.
Then, while using Technorati to see who is linking to the Photo of the Day, I noticed Sandy from Pollenatrix commented on the Calypso bulbosa photograph from a few days ago. That was great, but I then realized to my dismay that her tagline is “Botanical discipline, daily.”. I know that Pollenatrix has been around for a long time, and I'd certainly visited it a few times in the past. Sandy, will you forgive me? I must have liked the last bit of your tagline so much that I incorporated it into this one subconsciously - I promise it wasn't a conscious decision. I'll do a rethink on the one used for Botany Photo of the Day and alter it (or maybe someone has a suggestion to replace the word, “daily”?).
I'll explain the inspiration for the rest of the tagline in a future post.