Sandoval at Fresno

Shmuel Silinsky
Tue, 18 Jun 2013 21:21:55 PDT
Excellent, Leo.

I am convinced that the requirement for wetness, as well as continued
dampness to keep the seedlings going, is the reason so many cacti in
habitat seem to be all about the same size ( and I assume age). That
reflects that exceptionally wet year however long ago when they germinated.
I think I read that Carnegia (Saguaro) in habitat are not seen less than 50
years old - perhaps because of that rare wet year when they got going. Of
course, it is up to us to provide that rare year whenever we sow...

Shmuel Silinsky
Jerusalem, Israel
USDA zone 9

On Wed, Jun 12, 2013 at 1:28 PM, Leo A. Martin <> wrote:

> There are quite a number of tuberous cacti, so we can indeed consider them
> to be in a
> family of bulbs.
> Even large cactus seeds need light to germinate properly. Almost all
> cactus seed floats,
> which perhaps aids in dispersal, and not much floating seed is buried for
> sprouting in
> habitat.
> Uebelmannia gummifera sprouts and grows under white quartzite sand for
> several years
> before emerging. Its tiny seeds easily fall through cracks in adjacent
> sand particles,
> and its habitat on a slope of sand ensures there will be no flooding to
> carry seed to a
> less favored substrate. The sand transmits a lot of light, which one may
> see by putting
> a few millimeters of such sand in a transparent dish and looking up
> through it at a
> light.
> Along with light, another requirement for cactus seed sprouting is
> constant wetness, not
> dampness. In this cacti are also like dry-area bulbs.
> Leo Martin
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