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If you can – if you dare – plunge your face into one of these extravagant flower spikes. Close your eyes. Inhale deeply. Find yourself transported to another dimension, where a delicious scent pervades the atmosphere, sweet but not cloying, calling forth visions of floating in the fragrant air, care free, at peace.
On some California Buckeye trees, the flower spikes are reaching their peak in mid-May 2020. Others still have a way to go – keep an eye and a nostril out for their future development.
The flower spike consists of a mass of flowers around the sides, tapering to a tip. From that tip extends a different flower, larger, more showy, sensuous. Its stamens extend gracefully beyond the spike, waiting for a visiting pollinator.
What is the difference between these two types of flowers, the single one at the tip and those massed below? They both have stamens and anthers, male parts. I don’t know if both also have female flower parts, pistils and ovaries. I do know that the entire flower spike will produce one or at most a very few (perhaps up to three?) mature buckeye seeds. So perhaps only the tip flower actually produces a seed. (?)
The tip flower tends to reach maturity before those massed below. Can this act to reduce the chance of self-pollination?
Speaking of pollinators: the nectar and pollen of the flowers is toxic to (non-native) honeybees*. Perhaps hummingbirds suffice.
Today I see native Winter Ants exploring the flower spikes, burrowing down into the center of the flowers for sustenance – into both kinds of flowers, tip and massed.
Please leave a comment if you know about these characteristic California trees, precious to the Native Americans hereabouts.
Rodolfo Dirzo adds a compliment and some more information: "Your terrific photos show the amazingly exerted filaments with those prominent anthers; the female organs, are typically buried within the corolla, with a beautiful, whitish stigma therein."
[*ref: Little, Elbert L. (1994) [1980]. The Audubon Society Field Guide to North American Trees: Western Region (Chanticleer Press ed.). Knopf. p. 540. Via Wikipedia]
5/23/2020: Ten days later, the blossoms have filled out and are approaching decadence. I have added a few photos. Seeing a non-native European Honeybee taking sustenance from a flower, I note the danger to the bee colony, if not to the honey-eaters:
Is this really a non-native European Honeybee (Apis mellifera), one of the first insects to be domesticated, brought to the New World by European colonists in the early 1600s? Perhaps it didn't get the memo: "In addition to toxic seeds, the buckeye's leaves, shoots, and flowers are poisonous. All contain the neurotoxin glycoside aesculin, which is destructive to red blood cells. Although ruminants can feed on very young shoots without harm, and squirrels are able to tolerate the nuts, this toxin protects the buckeye from damage or death by grazing animals. As Ridgeway points out, 'the sweetly fragrant flowers of this tree provide a rich pollen and nectar source for native bees, hummingbirds, and many species of butterflies' and are toxic only to non-native honey bees. Honey bees that do survive after ingesting buckeye toxins reproduce “buckeyed-bees” that hatch with deformed, crippled wings or malformed legs and bodies." [Source: The Real Dirt Blog, written by UC Master Gardeners of Butte County, 3/22/2019. See Sue Ridgeway, The Bisexual California Buckeye – sinner or survivalist? UCANR website: http://sonomamg.ucanr.edu/Plant_of_the_Month/Aesculus_californica_-_California_buckeye/ .] Sue Ridgeway confirms that buckeyes have male, female, and "bisexual" flowers on the same tree, and adds: "Aesculus californica, bearing a profusion of pollinator attracting, erect, white, fragrant inflorescences (flower spikes) up to eight inches long, is polygamo-monoecious; a tree with both unisexual and bisexual flowers on the same tree. Because they have all four characteristics of a flower: sepals, petals, stamen and pistil, bisexual flowers are referred to as 'complete' or 'perfect' flowers." Of course, most flowering plants have only bisexual flowers. How dare they!