Arundinaria tecta Muhl.

Arundinaria gigantea ssp. tecta (Walter) McClure

Arundinaria tecta (Walter) Muhlenberg, 1813:14; 1817:191.

Arundo tecta Walter, 1788:81.

NEOTYPE.—Walter’s type has not been found. However, the living plant to which his brief characterization led me, has presented both the vegetative and the reproductive stages of its ontogeny, and many facets of its potential morphological diversity. The feature-combination characteristic of A. gigantea ssp. tecta—as elaborated in the descriptive key—is based on McClure 22000 (US), a series of specimens yielded by plants in a natural stand growing in and adjacent to a swamp lying between Stony Run Creek and the Pennsylvania Railroad, near Friendship International Airport, Anne Arundel County, Maryland, and by plants from the same source maintained under cultivation, as MBG 2762. They were collected over a period of years both at the original site, and from plants taken from the same source and maintained under cultivation, since 1955. This series of specimens constitutes the exclusive documentation of the characterization of subspecies tecta presented in the descriptive key.

Plants growing in the wooded swamp reach a maximum height of about 2.5 m. These have remained in a sterile (vegetative) state ever since my observations were initiated in 1952. Other sterile plants of the same taxon growing in upland clay soil on the opposite side of the railroad (until they were destroyed by earth fill) reached a maximum height of about one meter. Plants growing along the edge of the swamp push their rhizomes into the original gravel ballast along the railroad, where they produce culms 0.5 to 1.0 m tall. Here and there among these latter, little patches of culms in a depauperate condition may be found in flower every year. However, I have never found fruits produced in that situation. The reproductive organs in every floret are always more or less completely destroyed by the larvae of insects that pass this stage of their life cycle within the anthecia. Two plants among those maintained under cultivation in my garden (about 20 miles from the natural stand) flowered and fruited freely. The production of fruits by these cultivated plants is a circumstance attributed to the absence of the parasitic insect at the latter site. In all observed cases of flowering, whether in wild plants or in those grown under cultivation, the culms that flowered died in the same season, along with the rhizomes that remained attached to them.