Flowers: Sex, Pollinators and Pollinizers

Spring brings those beautiful flowers we all love so much. However, ever wonder just how it all happens? What happens behind the scenes of certain plants or trees for them to flower or fruit?

Sexual reproduction is an essential part of nature – even for trees and plants

Many plants are capable of reproducing from stolons, rhizomes, offsets, bulbs, tubers, root sprouts, and even stems and leaves that can take root. This form of reproduction – known as asexual – clones all of the offspring so they are genetically identical to their parents and to each other.

Asexual reproduction is just fine as long as the environment never changes

When the environment changes, the characteristics that allowed a plant to survive might no longer work for its posterity. A plant reproduced only by asexual means (all of its offspring identical, there came to pass a few years of below-normal rainfall, colder temperatures, more shade as nearby trees got bigger) it might go extinct then and there. If a species of plant is ever to colonize some new ground in a different place, with different environmental conditions, and all of its descendants were exactly identical, colonization is unlikely to be successful. When the offspring are all different, there is a better chance that at least some will be pre-adapted to a new or changed environment. Every seed has a different combination of genes – Some plants have flowers with only male parts, some only female. There are even some plants whose flowers have both male and female organs. Among the plants with both male and female parts, many are self-incompatible: They cannot fertilize themselves – defeating the benefits of sexual reproduction!

Sexual reproduction evolved in plants (and in animals) as a way to ensure variation among the offspring

The unique offspring produced by sexual reproduction have genes recombined from two different parents. Sex among plants takes place in the privacy of a flower. This occurs when a sperm cell (in a pollen grain) fertilizes an ovule (in the flower’s pistil) and creates a zygote which develops into a seed. The seed contains a recombined mixture of genes from two different parent plants. The mechanism that carries pollen from the stamen of one flower to the pistil in another flower is the pollinator. A pollinator can be an insect, a bat, a hummingbird, or even the wind. Many plants have flowers that require specific pollinators. Those pollinators tend to be faithful to the plants with which they co-evolved. You can increase the number of pollinators in your area by making conscious choices to include plants that provide essential habitat for bees, butterflies, moths, beetles, hummingbirds, and other pollinators. Below is a list of common plants to attract pollinators to your garden:

Aster, Aster spp. ¹
Bells or Phacelia, Phacelia spp. ²
Black-eyed Susan, Rudbeckia spp. ³
Catnip, Nepeta spp. ⁴
Coneflower, Echinacea spp. ⁵
Lamb’s ears, Stachys spp. ⁶
Lavender, Lavandula spp. ⁷
Oregano, Origanum spp. ⁸
Penstemon, Penstemon spp. ⁹
Redbud, Cercis spp. ¹⁰
Rosemary, Rosemarinus officinalis ¹¹
Sage, Salvia spp. ¹²
Sunflower, Helianthus spp. ¹³
Verbena, Verbena spp. ¹⁴
Yarrow, Achilliea millefolium ¹⁵

While the generic plants listed above are fairly adaptable, we urge you to go a step further and check the zone of your prospects – Look for native plants that are adapted to your climate

The plant that donates pollen to another plant is called the pollinizer. Many varieties of cultivated plants require a specific pollinizer in order to produce viable seed. Pecan trees are a great example. A Type I would be required to pollinate a Type II and vice versa. And more notably, a Type I can pollinate another Type I in the first half or the last of the cultivar’s receptive period. Same applies to a Type II. (Keep an eye out for a detailed Pecan Grow Guide in the near future). There is a significant amount of fruit trees that would also require a specific pollinizer.

Plants, sex, and reproduction go hand in hand. Plants thrive by attracting pollinators to their flowers. Pollinators thrive from the food source in plants, and pollination is essential to a healthy ecosystem. Without it, most plants could not produce fruit or set seed. If it were not for the flowers and pollinators, you would not be able to enjoy the fruits of their labor. Happy planting!