Photo 1: Korean Fir Abies koreana 'Horstmann's Silberlocke.' To view all photos, please open PDF.
Karl Foord, UMN Extension Educator
Cones are a big part of the ornamental appeal of evergreens. The cones provide spectacular colors, such as the iridescent cones of the Korean fir (Photo 1), and striking geometric patterns formed by the interlacing scales of red tamarack cones and light pink Acrocona spruce cones (Photos 2 and 3).
To view all photos in this article, please click here: Gymnosperms 7-1-11.pdf
Most but not all gymnosperms have male and female cones on the same tree (Photo 4). The male cones are short lived but the female cones persist for several years. The persistent female cones are the seed bearing structures of gymnosperm plants of which conifers are the most abundant. The word "gymnosperm" comes from the Greek meaning naked seed as opposed to other flowering plants termed angiosperms whose seeds are enclosed during pollination. Conifer seeds develop on the surface of the scales of the cone which open to receive the pollen to fertilize the egg cell and then close to protect the growing seed. Seed maturation can vary from 6 to 24 months depending on species. Most pines exhibit first and second year female cones (Photo 5). When the cone matures in the second year, the scales will separate to free the mature seed (Photo 6 and 7).
These seeds are the edible seeds we know as pine nuts. Worldwide some 20 pine species produce sufficiently large seeds for commercial purposes. The Stone Pine (Pinus pinea) has been the primary source of pine nuts In Europe and was domesticated some 6,000 years ago.
In North America three western pinyon pine species are the main source of pine nuts; Colorado pinyon (Pinus edulis), Single-leaf pinyon (Pinus monophylla), and Mexican Pinyon (Pinus cembroides).
Another fascinating thing about cones is the shape of the interior space between the scales of the cone. This space exhibits aerodynamic qualities enabling the cone to filter large amounts of pollen from the air and deposit them at the most advantageous position for pollination to occur.
I'll never look at a pine cone in the same way ever again.