E. sericeus rhizomes & stems [Hays Co., 20 July 2013]. (Click on each part for enlargement.)

by Bob Harms 

E. sericeus in central Texas develops subterannean stems (rhizomes). These were noted in calcareous clay soils in W Travis & N. Hays Co. Herbarium collections generally offer little below the base of the plant and don't permit determining the presence of rhizomes. Many show new shoots ascending from the stem base, but these lack lateral subterranean development and association with adventitious roots. With age the plants may also form lignotubers, as shown below.

Click on images for enlargements.

E. sericeus with subterranean shoots [Travis Co., 8 October 2012].

This development may be more apparent in late summer to fall as the plant matures, and may also depend on rainfall. The specimens shown here are no longer in flower (and the dried flowers have long peduncles).

A single E. sericeus plant with multiple subterranean stems from a central lignotuber 12 mm in diameter (in yellow box, enlarged below) [Hays Co., 20 July 2013].

Lignotuber 12 mm in diameter. Note the thick primary root at the lower right corner.