Words of the Week: Plume and Plumule

plume [ ploom ] noun: a plant part that looks like a feather (adjective, plumose: feathery)                                     plumule [ ploom-yool ] noun: the embryonic shoot of a seedling

 

The plumule rises above the cotyledons (the green seed leaves) in this seedling of invasive Nandina domestica. Its immature leaf is true to the mother plant, reddish-green and tri-pinnately compound.
Picture: Emmanuel Douzery CC BY-SA 4.0

We all know plumes as feathers on birds, frequently used or misused in past times to decorate ladies’ hats and plumules as the down feathers of birds, still used or misused in outerwear and comforters. In botany there is an actual structure called the plumule, which is the primary bud of a plant embryo or the first shoot. In botanical descriptions we often say a plant has feathery leaves, and the flowers and seed heads of grasses are also often described as feathery or plumose.

One such plant is Muhlenbergia capillaris (pink muhlygrass), a recommended native garden plant in our area with multi-season interest and value with its airy plumes of pink flower panicles. A commonly used non-native grass that can be invasive, but is handsome and has its uses in mass plantings or as a specimen is Miscanthus sinensis (Chinese silvergrass) and other members of that family, which have distinctive plumes. Another non-native species, this one from South America, is Cortaderia selloana (pampas grass), which bears male and female flowers on the plumes of separate plants. The plumes of the female plants are much showier, an attribute valued by garden designers. Their fullness comes from silky hairs covering the tiny flowers; the males lack these hairs. For that reason, most pampas grass is propagated vegetatively, by dividing a female clump.

The plume structure also appears in plants other than grasses. The fruit appendages of the Asteraceae called pappi permit seeds to be distributed by the wind. Depending on the source, some pappi are described as plumose. For example, the Manual of the Vascular Flora of the Carolinas describes the pappi of both Cirsium discolor (field thistle) and Tragopogon dubius (goat’s-beard) as plumose. The Flora of Virginia says that the pappi of field thistle have “numerous plumose bristles” but describes goat’s-beard pappi as “12–20+ awns or subulate scales.”

Some fern leaves are described as plumose, and many do look feather-like, such as those of Matteuccia struthiopteris (ostrich fern), which are said to resemble ostrich plumes, hence its common name. Asparagus plumosus (asparagus fern or lace fern) is quite a feathery-leafed plant and even has the attribute as its defining epithet. Keep in mind, however, that this popular house plant is not really a fern, it is a member of the asparagus family. While the pappi of goat’s-beard may be plumose, it is the inflorescences of false goat’s-beard or Astilbe, which are described as plumes.

References

Cortaderia selloana (pampas grass). Plant Toolbox. North Carolina State Extension.

Pampas Grass. Circular 983. University of Georgia Cooperative Extension Publications.

Radford AE, Ahles HE, Bell CR. 1983. Manual of the Vascular Flora of the Carolinas. The University of North Carolina Press. pages 1030, 1043.

Weakley AS, Ludwig JC, Townsend JF. 2012. Flora of Virginia. Botanical Research Institute of Texas. pages 304, 404.

 

 

 

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