fall blooming pattern: was RE: Flowers of Crete

Mary Sue Ittner msittner@mcn.org
Fri, 04 Nov 2005 17:47:28 PST
Dear Jim,

I found your discussion of why plants bloom in the fall very interesting. 
It certainly makes sense for the fall blooming Amaryllids in South Africa 
whose seeds so quickly start into growth. Some of these seeds can be 
growing weeks after flowering and without favorable conditions like plenty 
of moisture they will not survive.

The question or observation that I was raising, obviously not very well, 
was that in California, at least the parts that are considered to have a 
Mediterranean climate, even though growth does not start until the 
beginning of the rainy season, the bulbs that I'm familiar with do not 
bloom in the beginning of this season, but at the end. There are of course 
exceptions that bloom soon after the leaves appear in the late winter, 
early spring, but a lot of them come into growth from October to December 
but don't bloom until May to June, sometimes after their leaves have 
withered. There are areas of Southern California that don't get cold and 
have limited amounts of rainfall so you can't explain it completely by 
saying that the rainfall or cold would prevent flowers from being 
pollinated although in areas like mine excessive rainfall would certainly 
be a good reason to delay flowering.

Harold's comment that bulbs blooming (in the fall) would have a better 
chance of being pollinated because there is less competition does not 
explain why all the California bulbs bloom at a time when annuals, 
perennials, and shrubs are also in bloom so there would be a lot of 
competition. If they bloomed in the fall there wouldn't be much 
competition, nor is there a lot of rain then.

When some of us read the fascinating Dallman book, Plant Life in the 
World's Mediterranean Climates, we were impressed with the differences in 
these climates. California and Chile are completely dry in summer where 
some of the other places have less rain in summer, but still have some 
rain. In fact the rain in summer may be one of the factors stimulating 
Gethyllis to bloom in South Africa. Rachel has written that the fall 
blooming Amaryllids are often better after the summers they have had extra 
rainfall. When I visited Lauw in Southern France, he mentioned how dry the 
soil was and the handful I felt was not dry by California standards. When 
it first rains in California the soil is so dry that you can dig down in it 
afterwards and the soil is still dry. Would it take longer for our bulbs to 
start into growth? That was why I wondered if Chile had fall blooming bulbs 
or if most of their bulbs bloomed in spring or summer like ours. How about 
the Mediterranean areas of Australia? They don't seem to have as many bulbs 
as some of the other areas, but they do have some and as someone recently 
said all those wonderful ground orchids. I wonder how many of their 
"geophytes"  bloom in the fall.

In other words I was just curious to see if people had any theories about 
why there are fall blooming bulbs in some Mediterranean areas and not 
others. Perhaps this has partly been answered by the nature of the seeds.

Mary Sue

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