Botanic Names: Panic!

Our English word “panic” goes back to Pan, the goat-footed Greek god of nature, so I had always thought that the grasses of the genus Panicum shared that derivation. By extension, I thought the term “panicle” for the open, sort-of Christmas-tree-shaped inflorescence the Panic grasses display shared this derivation. Think again. The Panic grasses actually take their name from the Latin word panus meaning a swelling or the grain millet. Millet? We have two genera with that common name: Setaria, the foxtail grasses, which look nothing like Panic grasses, and the panicled Milium or Millet Grass, represented by only one species in Virginia: Milium effusum, Tall Millet Grass.

In the old books about grasses, Panicum is a very large genus. The Flora of West Virginia (1978) lists 35 species of Panicum. The Flora of Virginia (2012) only lists 11, because many have been renamed. The redesignated Panic grasses have gone into at least three other genera. Those that became Dichanthelium are the easiest to understand: they bloom twice in the same year (di = two, anth = flower) including the familiar Deertongue Grass, Dichanthelium clandestinum (hidden, because its fall inflorescence is often nestled among its leaves). They can be recognized by a common growth habit: straight up to a terminal inflorescence in the spring, then branching over the summer with several smaller inflorescences in the fall. Virginia also has four native species (3 further divided into 2 varieties each) of the genus Coleataenia (colea = sheath, taenia = narrow) including the common Coleataenia anceps, Beaked Panic Grass. One of two non-native species of the genus Urochloa (uro = tail, chloa = grass) in Virginia, Urochloa ramosa (branched), Dixie Signalgrass, was also once considered a Panic grass.

Panic grasses that remain in the genus Panicum include Switch Grass, P. virgatum (wandlike), and Witch Grass, P. capillare (hairlike). Panicum is also recalled in many flowers with panicled inflorescences, like Narrow-leaved Tick-trefoil, Desmodium paniculatum. But now you know there’s no need to panic.

Margaret Chatham

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