Plants could not proliferate as they do if they were as unintelligent as they seem to be. Actually, much of their activity would be considered quite ingenious if it could be observed in a more ‘human’ perspective. From their exploitation of pollinators to their aggressive tactics for competition with other plants, the behavior of plants is obviously very deliberate and purposeful.
Because they are so reliant on the weather, pollinators and so many other environmental factors, the life cycles of plants are on strict schedules. They must also adapt to diseases and all sorts of other pathogens. Fires and grazing animals are problems for many, but advantages to most.
Most seeds develop during summer and autumn. When they fall to the ground, they need to know to delay germination until spring to avoid frost and the likelihood of getting eaten. Seeds of many plants, particularly those from more severe climates, germinate only after being ‘stratified’ by a specific duration of cold weather. Such seeds need to be artificially stratified by refrigeration in order to germinate any differently from their natural schedule, or where winters are not sufficiently cold.
Many seeds require ‘scarification’ by digestion by animals that naturally eat them, or by the quick heat of a wildfire, to break or soften a hard outer coating that otherwise inhibits germination. Seeds that need to be digested actually rely on animals for distribution. Seed that need heat want to be the first to regenerate after a wildfire, before competing plants recover.
Goldenrain tree, and many maples and pines produce so many seeds that even if less than one percent germinate in the garden, they seem to be prolific. However, for more reliable germination of a majority of seeds, they should be scarified. The seeds of many pines that crave fire can be heated briefly in an already hot oven to simulate fire, just enough to heat the seed coat without roasting the seeds. Some people actually prefer to spread them on a piece of paper, and then burn the paper. Seeds that only need their hard outer coating to be damaged slightly might need only to be sanded lightly on sandpaper. I actually prefer to rub my canna or Heavenly bamboo (nandina) seeds on a brick or bit of sandstone.
Tony Tomeo 
I collected some canna seeds last fall. This spring sanded through the outer coat of about half of them, and left whole the rest. I soaked each batch of seed in a dish of water. Most of the scarified seed germinated and showed roots within a week or ten days. Few of the unscarified seed ever germinated at all. The little canna plants are now 6-9″ tall, and I either h ave to pot them up again or stick them in the ground.
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That is discouraging. It means that I should scarify the hundreds of canna seed that I may eventually grow. Fortunately, I gave most that are from fancier types away. Realistically, those that are from the more common types that are more prolific with seed should be given to someone who can use them as beads. (They are more genetically stable, so are more likely to grow into plants that are very similar to their parent.) I really do not need any more canna, and if I want more, I prefer to grow copies of what is already here. They just keep dividing! While sorting seed last year, I dropped three that did not seem to be completely developed into another canned plant, and all three grew. Of course, I can not discard them now.
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What I meant to say is that those three undeveloped seed that grew were not scarified. However, their underdeveloped exterior likely facilitated their germination.
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