YOUR DAILY DOSE OF BOTANY – July 2012
Carex Flower Terminology
by Scott Namestnik, snamestnik@orbisec.com
Summer is sedge season (who am I kidding… every season is sedge season!), and to be a real sedgehead you need to understand the botanical terminology necessary to make correct identifications. If you’ve ever been on a field trip led by a botanist, you’ve surely heard the term “perigynia” tossed around. So what the heck are perigynia? When you think of a typical flower you probably picture something like that on a trillium, with sepals, petals, stamens (male reproductive structures) and a pistil (female reproductive structure). Sedges (plants in the family Cyperaceae) do not rely on showy petals to attract pollinators, and thus they have evolved to have flowers that lack petals and sepals, or that have petals and sepals reduced to (often) inconspicuous bristles. Instead, sedges have modified flowers that consist essentially of a scale subtending the stamens and pistil. In the genus Carex (the true sedges, though all plants in the family Cyperaceae can be referred to as sedges), the flowers are imperfect, meaning that they are either pistillate (containing only female parts) or staminate (containing only male parts). Each pistillate flower (and ultimately the achene, or dry, hardened fruit) is surrounded by a bottle-shaped, sac-like structure, which is technically an altered bract (a bract is a modified leaf). This bottle-shaped sac-like structure is known as the perigynium (plural = perigynia). In the genus Carex, features of the perigynia are used to identify an individual to species. The next time you are in the field, be sure to check out the beauty and variety present in the perigynia of different Carex species.
If you have a question about plant terminology or morphology that you would like answered in a future edition of this column, send me an email at snamestnik@orbisec.com. I may not be able to address all requests given the space allotted for this column, but I will answer those that I can.