How Does Broccoli Reproduce?

How Does Broccoli Reproduce?
••• Ohio State University Extension

Did you know that a head of broccoli is composed of hundreds of unopened broccoli flower buds? The broccoli that you buy at the store or at a farmers market is the product of thousands of years of selective breeding, and many broccoli varieties have been bred for their tendency to resist bolting, or the opening of flower buds. Broccoli (​Brassica oleracea​) is an angiosperm, which means it is a flowering plant that reproduces by sexual means, via seeds. So, although most broccoli is harvested before its flowers begin to open, broccoli that is grown for seed is allowed to flower, and pollinators like bees help transfer pollen from one plant to another to begin the process of sexual reproduction in broccoli.

The Broccoli Family

Broccoli belongs to the mustard family, which is known as Brassicaceae or Cruciferae. Also referred to as brassicas, cole crops or cruciferous vegetables, many of the members of this family are closely related. In fact, many plants in this group are actually the same species, but they differ from one another enough that we think of them as completely different vegetables.

Broccoli, kohlrabi, cabbage, Brussels sprouts and cauliflower are all the same species of plants, ​Brassica oleracea.​ Bred for different traits, like tight green heads in broccoli and one large head in cabbage, these related crops are identified botanically with variety names. A variety name follows the genus and species names; for example, broccoli is referred to as ​Brassica oleracea​ var. ​botrytis,​ while cabbage is identified as ​Brassica oleracea​ var. ​capita.

The fact that many cole crops belong to the same species means that they can cross-pollinate. This means that pollen from a flowering broccoli head can fertilize the female part of a cabbage flower, and vice versa. This can result in seeds that carry traits from both parent plants, so the offspring of this cross-pollination may develop into something between a broccoli and cabbage plant.

Broccoli Seed Production

Although broccoli does not require pollination in order to produce an edible crop, it does need to be pollinated in order to reproduce. Broccoli is an outcrossed plant, which means that it requires cross-pollination for successful fertilization and seed production.

As we know, a broccoli flower may be pollinated by pollen from another variety of its species, like cauliflower. However, in order to produce a seed that is like the parent broccoli plant, a broccoli flower must be fertilized with pollen from another broccoli flower. Cross-pollination is the pollination of a flower with pollen from a different flower.

To produce broccoli seeds that are true to type, broccoli plants must be isolated from other plants of the same species, like cabbage and kohlrabi. Seed companies can accomplish this with large fields of the same crop, but it may be more difficult to accomplish in a home garden. That's why saving your own broccoli and cabbage seed may lead to unpredictable results the next year.

Other Broccoli Relatives

Brassicaceae is a large and diverse family. Many of the plants in this group originated in the Mediterranean, and there is evidence that humans have been breeding brassicas since 2000 B.C.

With a wide range of colors, flavors and forms, brassicas are important food sources all over the world. Along with broccoli, cauliflower, cabbage and kohlrabi, the family includes several other economically important species.

Like the species that broccoli belongs to, ​Brassica rapa​ encompasses several vegetables that are identified by variety names. Turnips are referred to as ​Brassica rapa​ var. ​rapa​, while Napa cabbage is identified as ​Brassica rapa​ var. ​chinensis​. Like broccoli, varieties of ​Brassica rapa​ are able to cross-pollinate other varieties of the same genus and species.

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