Thursday, November 20, 2014

Germination of Abronia, a new trick

Abronia, sand verbena, is a cool genus of an odd plant family - the Nytaginaceae "four o'clock family" - that has a number of members in coastal and desert western North America. Growing it is a pain; I've talked to now about a half dozen people who've said they gave up.

Pretty flowers reminiscent of garden Lantana, but not closely related!

Rick Karban and I are doing a project at Bodega on Abronia latifolia and I thought it'd be nice to have some in the lab for a future experiment. I poked about and found that others had some success using various methods: cold stratification, scarification with sandpaper, a ripe apple as a source of ethylene. Others just expressed frustration. I tried the apple, sandpaper and cold stratification without any success.

The cool, weird mine of Lithariapteryx abroniaeella, a mining caterpillar common on A. latifolia at Bodega.
Fortunately, I found a trick that's given me greater than >75% germination. Unfortunately, it is not possible on a large scale (i.e. a couple dozen plants are fine, a couple hundred would be maddening). Abronia seeds come wrapped in an anthocarp. Remove that - most will be empty, but 25-50% will have a seed. Take the seeds and soak them in DI water for a few hours - I generally do this from the morning to the afternoon, so about 4 hours, but I forgot about one batch and left them in for 24 and they were fine. Now the tricky part. Take a pair of fine tipped forceps and carefully remove the entire seed coat. In soaked seeds it will just come off. Be very careful not to damage the seed. Don't worry though, you'll get the hang of it after a few. Then place on wetted blotting paper under a light - don't allow it to dry out. In three or four days, the leaves will be green and roots will have started forming and you can transplant into well-drained soil.

A sand-verbena living up to its name. 
They grow slowly, but seem hearty (n.b. I've only had them alive for a month or so). I don't have seeds of any species besides A. latifolia, so I can't say it works for them, but I'd bet it does (and if anyone does have any, I'd love to get ahold of some). Do let me know if you try!