sex of pines

David R. Hershey dh321 at PGSTUMAIL.PG.CC.MD.US
Tue Oct 21 18:09:41 EST 1997


Pines are considered to be monoecious, so should be able to produce both
male and female cones. Wareing in Physiology of Forest Trees noted that
female cones often first develop when the trees are 7 to 9 years old, and
male cones at 10 to 15 years old. Dioecious gymnosperms include cycads,
ginkgo, most gnetophytes, and the following conifers, among others: yew
(Taxus), juniper (Juniperus), Podocarpus, Cephalotaxus, and California
nutmeg (Torreya californica). Sex in these species is genetically
determined. 

In angiosperms, sex of flowers is also often affected by plant age, as in
cucumber, and also by a variety of hormones, daylength, and temperature. 
In jack-in-the-pulpit, large plants are female one year then often become
male the next because they no longer have enough stored nutrients for
fruit/seed production.

*********************************************************************
David R. Hershey

Snail mail: 6700 Belcrest Road #112, Hyattsville, MD 20782-1340

Adjunct Professor, Biology/Horticulture Dept.
Prince George's Community College, Largo, MD 20772-2199

Email: dh321 at pgstumail.pg.cc.md.us

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On 21 Oct 1997, Grant R. Cramer wrote:

> What determines whether a pine produces female or male cones?
> 
> Grant Cramer
> Associate Professor
> Dept of Biochemistry
> University of Nevada
> 
> 






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