While I consider every flower to be perfect, technically it is not so. There are perfect flowers and imperfect flowers. Perfect flowers have both male and female parts – everything needed to produce seeds. Imperfect flowers are either male or female.
To review some basic biology, the male part of a flower produces the pollen from anthers. The anther sits atop a long, skinny filament altogether called the stamen. This structure is exaggerated and obvious in a lily flower.
The female structure is called a pistil and consists of a stigma, style, and ovary. The stigma is the surface that the pollen grains land on to fertilize the ovules in the ovary. Both of these structures are in perfect flowers.
Plants that have perfect flowers invest a lot of energy in luring insects into them to achieve pollination. Large, brightly colored petals, fragrance, and sometimes even little landing pads for insects lure them in to feast on nectar, all the while inadvertently picking up pollen and dropping it off onto the next flower.
Then there are the bees that go out on special pollen foraging trips, scooping it up and stuffing it into their little leg baskets, a.k.a. bees knees, which they bring home to feed their young. All this while, they have spread pollen throughout many stigmas. Such is the world of perfect flowers. They are the ones we like to pick and smell.
Soon after all this rain stops we will be experiencing massive quantities of pollen drop from a variety of trees. One of the first we experience is the pollen from the native Cedar tree, Calocedrus decurrens. Each late winter, yellow pollen seems to be everywhere, covering everything. This is the result of imperfect flowers. The structures of the male and female parts vary from those in the perfect flower. The pollen producing structures are called catkins.
The cedars have imperfect flowers and are wind pollinated. To fertilize the female flower structures the pollen needs to travel by wind. Nature wants to prevent inbreeding, it wants the pollen to fertilize another tree, not its own. So, the pollen is dry, lightweight, designed to travel miles to reach another specimen to fertilize, and super abundant to assure fertilization. When a plant doesn’t have to lure insects in for pollination, it uses its energy by producing abundant pollen.
Here’s another category of division. If both male and female flowers are on the same plant it is monoecious, meaning, one house. Perfect flowers are already in that category, and many familiar plants with imperfect flowers are of this category. The native cedars, the true cedars (Cedrus deodara and C. atlantica), all oaks, walnuts, pines, alders, birches, corn, and squashes are some examples.
Squashes can trick people sometimes because the male flowers just dry up and drop off without setting fruit. They are always the first flowers on the squash plant and it’s one of Nature’s mechanisms to prevent inbreeding. The insect attracted to the male flower (it looks so like the female flower) searches for the nectar but only gets doused with pollen. Then it finds a female flower on a different plant, and while diving in for the nectar, pollen gets rubbed off and onto the stigma fertilizing it. So don’t fret when you get no fruit from your first squash flowers!
Then there are imperfect flowers that are on separate plants. That is, all male flowers are on one plant and all females on another plant, making an entire plant either male or female. The name for this setup is dioecious, meaning two houses. Some examples are holly, kiwi, cannabis, and Ginkgo. In order to get those gorgeous red berries in the winter from your holly plants there must be at least one male plant nearby. Many nurseries now offer both a male and a female plant in one pot to assure fertilization. With kiwi, if you want fruit you must plant a male and a female plant. With cannabis, the males are usually destroyed so as not to produce seeds in the female.
The Ginkgo tree (Ginkgo biloba) is one of my favorites. It is an ancient tree species, earliest leaf fossils date it at 270 million years ago and it has not changed a bit since then. While it used to cover many parts of the earth until the dinosaur wipeout, it remained in a small region in China and humans have carried it out around the planet again. It grows slowly to be 25-50 ft. tall and achieves a majestic oak-like spread in maturity. It is widely adaptable to soils, climatic zones, tolerates urban environments and air pollution, moderate drought, and I’ve read that it is deer resistant, although I have not yet tested it. And its stunning golden fall foliage make it truly a worthy specimen tree, suitable as a street tree and a landscape tree. BUT, as I said, it is dioecious and you really most likely want the male tree. The females, if a male is somewhere nearby, produce a fruit that drop to the ground, quickly rot and smell like dog poop. Inside there is a seed that is a Chinese delicacy…but you’d have to deal with some unpleasantness first. So beware, I’d suggest the male for most purposes.
Perfect and imperfect, monoecious and dioecious, insect pollinated and wind pollinated, it all reflects on the amazing diversity Nature has created to assure reproduction. Non-technically, it’s all pretty perfect to me.