Pine cones (herein referring only to the true female cones) have a peduncle (stem) which attaches to the branch (usually the upper branches) of the tree and this continues through the entire length of the cone as the rachis (axis). Multiple cone scales arise along the length of the rachis in a helical fashion to give the cone most its mass and characteristic external appearance. The cone scales each carry two ovules which usually develop into seeds on their ventral (the side closer to the distal end of the cone) surfaces. Hence these scales are also called ovuliferous scales or seed scales. Lack of pollination, genetic defects or other mishaps may result in sterile (or no)seeds. A smaller bract scale subtends and merges with the cone scale dorsal surface and is quite inconspicuous. (The bract scales can be clearly seen on Douglas fir cones because they are longer than the seed scales and protrude as the familiar trident tags.)
pine cone is an organ on plants in the division pinophyta(conifers)that contains the reproductive structures. It is the part of a tree that lets the tree reproduce. Its formal name in botany is strobilus, plural strobili.
The familiar woody cone is the female cone, which produces seeds. The male cones, which produce pollen, are usually smaller and much less conspicuous even at full maturity. The individual plates of a cone are known as scales.
The male cone (microstrobilus or pollen cone) is structurally similar across all conifers, differing only in small ways (mostly in scale arrangement) from species to species. Extending out from a central axis are microsporophylls (modified leaves). Under each microsporophyll is one or several microsporangia (pollen sacs).
Conifer cones and their seeds have been used for lots of different purposes. They are often used for decorations. Some seeds, for example, the seeds of pinyon pines, are used in prepared foods and baking
It is not a fruit and it is not a seed. What most of us call a “pine cone” is really a cluster of highly modified woody scales tightly packed together to protect the developing conifer seeds inside. Conifers are the cone bearing trees; and while most everyone knows that pines and spruces belong to this group, the conifers are represented by over 550 species, including hemlocks, firs, cedars, cypresses, yews, and even the common indoor Norfolk Island Pine. The term conifer is often used as a synonym for evergreen, and that really isn’t correct. Some conifers are not evergreens (examples: Bald Cypress, Dawn Redwood, and Larch), and many evergreens are not conifers.
Every conifer species has male and female cones. While both the male and female cones start out small, the males do not grow to any appreciable size, and are shed from the plant soon after releasing pollen. They are rather inconspicuous and often go unnoticed. The female cones grow large after pollination, maturing in a matter of months for some species, and years for others. Mature female cone size varies with species, from as small as ¼ inch to over 2 feet in length.
Most conifer species produce male and female cones on the same individual. But some, like the yews and junipers, appear on separate plants. Not all conifers make scaly cones. Yews and junipers have a fleshy covering over each seed that resembles a small fruit more than a cone.
While developing, the scales of female cones are clasped together and usually held tight by resin. When the seeds between the scales reach maturity, the cone responds by changing color from green to brown, and separating its scales to expose the seeds that will soon fall out. For some species, the cones remain tightly closed until exposed to very warm temperatures. New Jersey’s native Pitch Pine, for example, will remain closed on the tree for years until exposed to temperatures over 130oF. The strategy here is that the tree will not release seeds until after a forest fire has burned the twig and leaf debris from the forest floor, making the site suitable for seedling germination and growth.
Conifers have two basic means by which their seeds are dispersed; wind or animals. Wind dispersed seeds are usually small, with a prominent wing that allows the seed to be carried far from the parent plant by a breeze. Seeds that rely on animals for dispersal are larger and non-winged. They provide a nutritional reward for the animals, and those not consumed immediately are usually carried some distance from the parent plant and hidden. If not recovered, they germinate and grow.
Conifer cones and their seeds have been used for a variety of purposes. Besides the obvious use of cones for decorations, some seeds, like those of pinyon pines, are used in prepared foods and baking. The seeds of junipers provide the distinctive taste of gin.
The conifers represent a very successful part of the plant world. They enjoy a worldwide distribution, and have been around for the past 200 million years, producing their unique cones as their means of reproduction.