In much of the world, the day we're about to have today would be a summer day. It's November 5th, yet we have not yet had a killing frost. The garden is still full of impatiens, scarlet sage, coleus, cuphea and other tender annuals. The temperature is predicted to be in the mid-70s F today and thunderstorms are predicted for tomorrow. This in not so-called Indian Summer; that comes after a killing freeze. This is an extension of summer into fall, and some might see it as a portent of the Mediterraneanization (choke on that, spell check!) of our climate. And I've got loads of things to do in the garden. So I won't be tricked into sitting here at the keyboard all day. But I'm finding this topic of fall blooming bulbs fascinating. I my earlier post I largely ignored the role of pollinators. But the more I think about it, the more important the role of pollinators seems to be. Harold pointed out two advantages of autumn bloom: less competition for pollinators and a reduced likelihood of rain damaging the pollen. These factors would indeed prove advantageous to plants which are already by nature autumn flowering. Alberto pointed out that autumn flowering positions the ripening seed to take advantage of the long growing season ahead. Again, this undoubted advantage would work to favor plants which are already by nature autumn blooming. But contrast that with the situation in Californian themdiaceous plants which Mary Sue pointed out. Paul focused on the significance of the seasonal activity of pollinators, and really hit the nail on the head: his explanation accounts for the very existence of seasonal flowering in some plants. Paul's explanation makes sense in a climate where pollinators and plants are active throughout a long season. Paul said that if an ancestral plant population were active all year, but its pollinator came to be active only part of the year, eventually the plant flowering season would shift to reflect the period of activity of the pollinator. If the pollinator's major season of activity were autumn, then you would get autumn blooming plants. Pollinators are probably the major cause of fall blooming plants. Let's take it a step further. Paul's scenario would account for the emergence of a seasonal flowering flora anywhere. I'm particularly interested in what happens in areas where relatively mild winter areas adjoin areas with severe winters. The Mediterranean basin is an example of such an area. What makes the flora of this area interesting is that it includes taxa with members which are fall blooming and late-winter and spring blooming, and taxa which are fall blooming and have obvious relatives which are spring blooming. Because plants which bloom in the spring provide pollen and nutriment to pollinators, it makes sense that the competition of pollinators for the earliest pollen sources would cause the plant populations they pollinate to become progressively earlier in their flowering time. The pollinators select plants for early bloom, and they thus cause plant populations to bloom earlier. In areas with severe winter cold, this process of selection for early bloom can only go so far: the plants will not be selected for bloom any earlier than the pollinators can be active. If the pollinators are not active during the winter, then the plants are not selected for winter bloom. But in areas with comparatively mild winters, the opportunity exists to allow pollinator activity all winter. As a result, an ancestral spring-blooming stock could be selected for progressively earlier and earlier bloom until the plants in question bloom earlier and earlier in the spring, earlier yet into the winter and finally earlier yet into the fall. It's in this sense that pollinators can cause plants to become fall blooming. In a climate with harsh summer conditions, this process of earlier and earlier bloom would stop at the autumn blooming phase (if the pollinator is not active during the harsh summer, then there would be no selective pressures to continue this process even earlier into summer). No one thinks it's unusual when asters or chrysanthemums bloom in the fall. Maybe the reason this does not seem unusual is that the plants themselves have been in place growing all spring and summer in the time leading up to bloom With our autumn blooming bulbs, one of the things which makes their bloom so remarkable is that it seems to come from nowhere. They just suddenly pop up out of the ground. The other thing which makes it remarkable is that these autumn blooming bulbs have obvious relatives which bloom in the spring. Many bulbous taxa seem to have been pushed to three extremes: fall blooming at the beginning of a fall-winter-spring growing cycle, late-winter/early spring bloom in areas with severe winters, and summer blooming at the end of the growing season (the themidaceous/Calochortus cycle) in some dry summer areas. Each provides advantages to the taxa in question: reduced competition for pollinators, specialized pollinator relationships and enhanced seedling survival. Jim McKenney Montgomery County, Maryland, USA, USDA zone 7, where I'm off to plant lilies and peonies and to forget about prophylls and themidaceous things (that word themidaceous would have drawn a total blank from me two years ago).