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Monday - October 08, 2007

From: Leander, TX
Region: Southwest
Topic: Groundcovers
Title: Marbleseed (Onosmodium sp.) propagation and use as groundcover for
Answered by: Nan Hampton

QUESTION:

I am interested in any information, esp. propagation & suitability as a landscape plant, (possible ground cover?) for marble seed. I have found it growing in deep shade on stream banks. It has a 4--6" strap-like, dark green leaf. The seed is perfectly round, smooth and white, and about the size of a small piece of perlite. I have asked other native plant friends, but no one knows of this plant and I have been told it is rather rare.

ANSWER:

There are two species of marbleseed, Onosmodium helleri (Heller's marbleseed) and Onosmodium bejariense var. bejariense (soft-hair marbleseed) that occur in Texas and both have been reported from Williamson and Travis counties. Of the two, O. helleri is the rarer, endemic to only eight counties of the Edwards Plateau and Lampasas Cut Plain. I suspect you have found O. bejariense var. bejariense (syn. Onosmodium molle), but you can find a key in Shinners & Mahler's Flora of North Central Texas on pp. 453-454 (the entire book is accessible online in downloadble pdf files) to determine which you have found. Both species are attractive but can grow as tall as 3 feet so they may be more suitable for including as accent plants rather than as a groundcover.

From Sean Watson, the nursery manager of the Lady Bird Johnson Wildflower Center:

"We sow seeds in Spring in our greenhouse, using sterile seed germinating mix and intermittent misting (about every hour for 6 seconds). Just cover the seed with media, about 1/8" deep. They do benefit from some shade when trying to germinate them. I have also sown them as late as July with success (again I gave them more shade)."

There is also information about the propagation of O. bejariense var. bejariense (syn. Onosmodium molle) from Dave's Garden.com.

Onosmodium helleri