As long as this blog has been running, almost three years now, you’d think I would have written a post about flowers already. Apparently not.
Beautiful, fragrant, and occasionally edible, flowers are designed to attract pollinators. It’s really a case of “sex sells” - the flamboyant structures, bright colors, and heady aromas of flowers are all designed to propagate the species by attracting pollinators. Pollinators move pollen (male) to a place where it can reach the egg or ovule (female) and allow fertilization to occur.
Flowers are the reproductive organs of an entire group of plants called angiosperms. Angiosperms are the largest group of plants on Earth and they make up a huge portion of our food supply. Angiosperms use flowers to create seeds that are covered by a protective, often edible, outer covering. The fruit that we eat is nearly always the ovary of a flower. This includes cucumbers, melons, apples, peaches, avocados, squash, tomatoes, eggplants, and, well, really, the list is too long to include here, but you get the idea.
So, what makes a flower a flower?
Some flowers are male, some flowers are female, and some flowers are both, though not always at the same time. Flower parts are either vegetative or reproductive. These parts are generally arranged in a whorl around a central stem. If a flower has parts (petals, stamens, or other parts) that are divisible by three, it is probably a monocot. If it has flower parts that are divisible by four or five, it has been, most likely, classified as a dicot. That classification system has recently gone through some changes, due to genetic research. Many dicots are not classified as eudicots.
Looking at the base of a flower, you will see the vegetative perianth. The perianth is the outer part of a flower, made up of the green sepals (calyx) and colorful petals (corolla). The reproductive parts of a flower are divided by gender. The Greeks called them gynoecium (woman’s house) and androecium (man’s house).
Woman’s house The female aspect of a flower is called the pistil. The pistil has three parts: the stigma, style, and ovary. The stigma has a sticky tip, which is where pollen is received. The style is a long, tubelike structure that leads to the ovary. The ovary contains egg cells called ovules. Some scientists call the pistil a carpel. I don’t know why.
Man’s house The male aspect of a flower is called the stamen. Stamens are pollen producing anthers held on top of filaments.
Floral attachments and arrangements
Most flowers grow at the end of a long stem, called a peduncle. When a single flower is made up of many tiny flowers, it is called an inflorescence, and the individual flower stems are called pedicels. Sunflowers and daisies are examples of inflorescence. Some flowers may be directly attached to the parent plant, with a very small or absent stalk. These flowers are called sessile. Crocus flowers are sessile. The place where stem meets flower is called the torus or receptacle.
Flowers are classified according to their symmetry. If you cut a flower in half, down the middle, you will either have a ‘regular’ (actinomorphic) flower, or an ‘irregular’ (zygomorphic) flower. Regular flowers will have identical halves, no matter how they are bisected. Roses are regular flowers. Irregular flowers will only look symmetrical along one cut. Orchids and snapdragons have irregular flowers. Regardless of their symmetry, flowers are all about reproduction and sharing genetic information through seed production. Sometimes, they even help with dispersal.
Some flowers have structures that aid in seed or spore dispersal. These structures are called diaspores, and you have already seen them. They are the helicopters (samara) of maple trees, the flying seeds (achenes) of dandelions, and the spikelets of foxtail grasses. Tumbleweeds are giant diaspores.
As much as we love to eat the fruit of a flower’s labor, sometimes the flower itself is edible. Borage, nasturtiums, chive, basil, squash, dill, and cilantro flowers are all edible and they make nice colorful additions to salads. Of course, if you eat a squash flower, you won’t get the squash fruit. Also, not all flowers are edible. Some flowers can make you very sick, or worse. Always check before eating something new, and give it a rinse. There may be chemicals, pollutants, bug poop, or live insects hidden in a flower’s nooks and crannies. Also, some edibles flowers, such as dandelion, taste fine when young, but can get bitter as they mature.
Flower pests and diseases
Flowers are susceptible to certain pests and diseases. Common flower pests include citrus bud mites, budworms, voles, thrips, Eriophyid mites, and, of course, aphids. Diseases that specifically attack flowers and buds are petal blight, aster yellows, gray mold (Botrytis), phytoplasmas, olive knot (pseudomonas spp.), and blossom blight (brown rot).
When a plant suddenly sends up a central stalk and flowers, it is called bolting. Bolting usually occurs in response to extreme heat or drought. You could say that it is a panic response to harsh conditions, but it is also a normal part of many plants' natural life cycle.. Rhubarb, lettuce, spinach, bok choy, and other cool season crops will often bolt if grown in the summer. Once a plant starts to bolt, much of the flavor is lost.
Removing spent flowers is called deadheading. By removing flowers just before they start to whither, you can trick plants into thinking they have failed to reproduce, so they will make more flowers. More deadheading, more flowers, more deadheading… you see where this is going.
Growing flowers is an excellent way to attract pollinators to your garden or foodscape. They look lovely on the dinner table, too!
You can grow a surprising amount of food in your own yard. Ask me how!