The Answer is blowing in the wind?

The Answer is blowing in the wind?By Spencer Shaw
When we discuss seed dispersal you may invariably think of those gaudy members of the flora kingdom who use birds and mammals to spread their seed by covering their seed in a fruit that’s attractive to the animals. It could be said that these plants were the first beings to master the art of advertising. That is to say – the art of making you believe, that you just have to have their fruit no matter how low the food value, because its such a lovely colour. Sure some fruit are relatively nutritious and the lucky bird or possum that’s eaten them can lay back on a warm sunny branch and relax while the digestive processes take place. However most fruit are designed to pass straight through digestive systems as quickly as possible leaving birds feeling hungry and  having to eat even more fruit – how devious! Before you go thinking how superior you are and how dumb birds are for getting themselves trapped in a vicious circle like that, may I remind you that at least the birds only get sucked in by the advertisers when it comes to food…
Then there are those free spirits of the botanical kingdom who throw caution to the wind, well maybe not caution but at least their seeds. Prior to plants taking advantage of the digestive systems of animals as a means of dispersing their seed, wind dispersal was the only way to spread your seed (hmm. there’s got to be a joke in there somewhere?). Ferns and mosses were amongst the earliest of plants and produce spores that are wholly spread by wind. Tree fern spore is particularly good at getting about. Now I don’t want you to panic but you’re probably inhaling some at the moment, its everywhere! Fern spore will germinate on any moist, shady and bare patch of soil which is great for all you revegetators out there because ferns will turn up in your patch of developing forest all by themselves when the conditions become right.Besides the ferns many trees have evolved to spread their seed in the wind. Some familiar examples are the ancient conifers (excluding the Bunya of course) whose flat seeds are blown about in the summer storms and the sand like seed of eucalypts that are released to float on the breeze after a bush fire.  The great limitation of wind dispersal is of course the wind itself. After all what happens if a few weeks of calm weather set in when you’ve got a big crop of fruit on! Also unless your seed is particularly small then you’re going to be lucky if your seed goes any more than a kilometre. This poses a big problem for the spread and maybe survival of some of the wind dispersed species in the fragmented forests of SouthEast Queensland.When it comes to tree planting we should make sure these species are on our planting lists particularly if no parent trees of the same species appear close by. Next time I will discuss a group of plants that can have even more problems spreading their seed, those who’s dispersal agents are now extinct!
Some Wind Dispersed Seed:Ailianthus tryphisa                                    Araucaria cunninghamiiArgyrodendron actinophyllumArgyrodendron sp. Kin KinCaldcluvia paniculosaCallicoma serratifoliaDaphnandra sp. mcpherson rangeDoryphora sassafrasFlindersia austalisFlindersia bennettianaFlindersia schottianaFlindersia xanthoxylaGrevillea hilliiGrevillea robustaHymenosporum flavumPentaceras australisPseudoweinmannia lachnocarpaToona ciliataTristaniopsis laurina