Living fossils have hot sex(lowering plants or angiosperms cycads ar...)

Date:10/4/2007

lowering plants, or angiosperms, cycads are gymnosperms the group that also includes modern conifers such as pines and firs. Cycad plants are male or female. They look similar to palms or ferns, but are not related to either. Instead, cycads are a group of plants that the fossil record suggests have been around since the Permian Period roughly 290 million to 250 million years ago.

The cycad species in the study has most of its trunk underground. Leafy fronds stick up above ground and a single cone male or female grows in the middle of the fronds. The cone looks similar to a pine cone but is green at early stages, and then turns yellow. The scales of the cone normally are close together, but tiny spaces between the scales open slightly during the period when pollination occurs. The spaces provide a way for the insects to gain access to the pollen in male cones and the eggs in female cones.

It once was thought that pollination of cycads occurred randomly by wind blowing the pollen from male cones to nearby female cones. However, the eggs contained in the female cones of some species of cycads including Macrozamia lucida, the species studied by Terry and colleagues cannot be reached by wind-blown pollen because the cone scales are too tightly packed.

So there had to be another way for pollination to occur. In an earlier study, Terry showed that one species of thrips Cycadothrips chadwicki pollinates the Macrozamia lucida cycads.

In the new study, she discovered the hot, smelly details of how that happens.

An individual cycad plant has a pollination period known as coning season once a year to once every several years. That period lasts only four weeks or less. Then theyre done and the cones disintegrate, Terry says.

During those two weeks, cycads can increase the temperature of their cones particularly the male cones each day between 11 a.m. and 3 p.m. The male cone can heat itself up 25 d
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Contact: Lee Siegel leesiegel@ucomm.utah.edu 801-581-8993 University of Utah Source:Eurekalert

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