Questions about seeds from hot and dry summer areas
Jane McGary (Wed, 18 Jun 2003 14:22:43 PDT)
Jamie asked,
you mentioned "tumbleweed" dispertion. Is this a mechanism used by the
drumstick Alliums? It would explain their inflorescenses and the fact that
they typically free themselves from the bulb before they are ripe. Perhaps
to start a journey and release ripe seed while underway?
Yes, that is exactly what the term "tumbleweed" refers to. Many plants from
dry, open habitats have this characteristic. Lewisia rediviva is a good
example from the dicot group. Its plants often can be found in colonies in
the lee of rock outcrops, where the dried capsules are deposited by the
wind flowing over the outcrop, and where the seedlings find a little extra
moisture. ("Tumbleweed," by the way, is the American common name for
Amaranthus albus, an introduced weed.)
Jane McGary
Northwestern Oregon