Birds and Bees – Seeds

This year we are learning more about plant propagation in a series called "Birds and Bees." In the last installment, our topic was the process of plant fertilization, which results in a seed that is comprised of the endosperm (nourishment for the seed), and an embryo (the immature plant within a seed). This time we are taking a closer look at seeds and seed parts.

Seeds can be distinguished between monocotyledons and dicotyledons (also called eudicots). Monocots are flowering plants that bear a single cotyledon  (one seed leaf), and usually have long, stalkless leaves with parallel veins (such as maize, grasses, lilies, and palms). Dicots are flowering plants that bear two cotyledons (two seed leaves), and usually have broad stalked leaves with netlike veins (like roses, daisies, beans, and oaks). Seed parts are similar for both categories, with slight variation.

Seed parts for beans (dicots) and corn (monocots)

As always, terminology is important for understanding seeds and seed parts.

Term	Description
Seed Coat	The protective coating around the seed.
Cotyledons	The food storage structure in seeds, and the first leaves that appear for seedlings.
Epicotyl	The region above the cotyledons.
Radicle (or Plumule)	The embryonic root.
Hypocotyl	The embryonic axis. This is the location between the root and where the cotyledons attach.
Endosperm	The food storage tissue in seeds.
Pericarp	The fruit wall in stone fruits, like peaches, pears, and apples. The pericarp is fused with the seed coating. (Not shown)
Miscellaneous	Monocot specialization: Coleorhiza – the sheath that envelops the radicle in monocots, such as grasses. Coleoptile – the protective sheath that covers the emerging shoot in monocots, such as grasses. Scutellum – the shield-like cotyledon of some monocots, such as barley and rice.

HTML Tables

Learn More:

• Botany for Gardeners, by Brian Capon (Timber Press 2005). See Part V Reproduction, Chapter 9, “From Flowers to Fruits”.
• Pollination and Fertilization, derived from Pollination and Fertilization, by Robert Bear and David Rintoul, for Open Stax, Rice University (Creative Commons).