Birds and Bees – Flower Parts

If you’re going to study something, it is a good idea to learn its terminology. Terminology gives you a common language for talking with others; searching for information; and understanding new concepts. Before we delve into plant propagation this year, let's learn the names of key plant reproductive parts, and what they do. I’m turning to one of my favorite references, How to Identify Plants, written by H.D. Harrington, and illustrated by L.W. Durrell; and using this diagram by Maria Ruiz.

Mature flower parts (by Maria Ruiz, public domain)

Plant reproductive morphology—the study of the physical form and structure of plant parts that are related to sexual reproduction—is complex and varied and fascinating. To narrow our scope, let’s start with basic flower parts for a complete (has sepals, petals, stamens, and pistils present) and perfect (has both stamens and pistils) flower. See, it is already complex!

Structure	Description
PISTIL	The seed-producing organ, or female reproductive parts (think, “pistil-packing mama”), consisting of: Stigma – the part of the pistil that receives pollen, typically near the apex. The stigma may be hairy, protruding, or sticky. Style – the stalk-like part of a pistil connecting the ovary and stigma. In summary, the pollen grows through intercellular spaces in the pistil to create a tube, through which fertilizing sperm cells can travel to reach the eggs, or ovules. Ovary – the part of the pistil that contains the ovule. The ovary may have a single chamber, or locule, or many. Walls, called septum, separate locules. Each locule contains one or more ovules, connected to the placentae in various configurations (such as parietal, axile, basal, or free-central). The diagram shows an axile placentae. Ovule – the structure that develops into a seed.
STAMEN	One of the pollen-bearing organs of a flower, or male reproductive parts, consisting of: Anther – the pollen-bearing part of the stamen. Filament – the thread-like body that supports the anther. Microsporangium – the container structure that holds small spores or microspores.
PERIANTH	The flower envelope, or “bling” that lures pollinators, consisting of: Corolla – the inner series of the floral envelope; a collective name for petals. Calyx – the outer series of the floral envelope, especially when it differs from the corolla in size, color, or shape. Sepal – part of the outer whorl of the flower envelope, or calyx, which is usually green.
PLUS	Plus a few more terms: Floral axis – a modified stem which bears the essential reproductive organs (like stamens and pistils), and supportive organs (like sepals and petals). Nectary – a gland or tissue that secretes nectar. Nectar attracts pollinators, and provides them with nutrients (in a mutually beneficial exchange). Articulation – a joint or node between two separable parts, like the pedicel and the flower. Pedicel (Peduncle) – these terms are sometimes used interchangeable for the stalk to a flower, but Harrington uses this distinction: (1) Pedicel – a stalk to a single flower of an inflorescence (a complex flower configuration); and (2) Peduncle – a stalk to a solitary flower or an inflorescence).

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Well, that is a great start on terminology for complete and perfect flowers (those that come fully loaded with all reproductive flower parts), versus other interesting configurations. Once we master these terms, we can tackle terms for some of these fascinating variations.