(Ohio’s native and nearly-native conifer genera)


Gymnosperms are the “naked seeded” plants. They do not produce flowers, hence there are no ovaries completely enclosing ovules, and no fruits completely enclosing seeds. These are the cone-bearing plants, producing uncovered (naked) seeds in pairs at the base of female cone scales. Gymnosperms are woody plants, mainly needle-leaves evergreen trees that are in most instances monoecious (bearing unisexual structures on different parts of  the same plant).

Here’s a pine (alas, a cultivated species, Austrian pine, Pinus mugo) that demonstrates the signature features of conifer reproduction. First, see a branch with pollen-producing cones.

Pinus mugo staminate

Pollen-producing cones of Austrian pine.

Uniquely among our conifers, pine (genus Pinus) reproduction takes two years. During the beginning of the first year, at the same time that the male cones are sending clouds of yellow pollen into the air (ha-choo!), the newly-formed female cones are teeny-teeny tiny-tiny little things, barely distinguishable from ordinary branch tips.

Pinus mugo ovulate yr0Austrian pine ovulate cone at beginning of year one.
Pollination occurs at this stage.

Some lucky pollen grains that happen to land on a drop of sticky fluid produced by the female (ovulate) cone get drawn into the cone, where they remain dormant for a year. During that year, small multicellular gametophytes –two per cone scale –develop within the cones. These 1-year old cones are medium-sized, greenish, and tightly closed.

Pinus mugo ovulate

Austrian pine cones at beginning of 2nd year.
Pollination occurred the year before. Fertilization occurs now!

At the beginning of the 2nd year, fertilization (egg + sperm -> zygote/embryo) occurs, using pollen grains that were sucked into the cone the previous year. Thus in pines there’s an interesting peculiarity in timing: pollination and fertilization occur an entire year apart! At the beginning of the second year, sperm from the pollen grains that were captured one year ago fertilize the egg in the gametophytes at the bases of the scales, which develop into winged seeds in pairs at the bases of the scales. The cone scales separate and the winged seeds drift away at the end of the second year. By the time we tend to notice them, the familiar dark dry woody pine cones have released their seeds, although careful examination sometimes reveal a few stuck seeds  remaining.

Austrian pine at end of 2nd year.
Cone scales have spread apart and released the winged seeds.

Below, see a very informative branch of Virginia pine that shows all 3 life stages of ovulate pine cones. On the left is a cone that originated at the beginning of the current season (pollination has taken place, but not fertilization). A little left of center is a one-year old cone (fertilization has just occured within a recently formed female gametophyte). On the right is a 2-year old cone that has recently released its seeds.

Virginia pine branch with all 3 ages of cones.


 Abies balsamea (L.) Mill.   BALSAM FIR  Pinaceae  ornamental tree
 Juniperus virginiana L.   EASTERN RED-CEDAR  Cupressaceae  native tree
 Larix laricina (Du Roi) K. Koch   EASTERN LARCH  Pinaceae  native tree
 Picea rubens Sarg.   RED SPRUCE  Pinaceae  ornamental tree
 Pinus strobus L.   EASTERN WHITE PINE  Pinaceae  adventive tree
 Pinus virginiana Mill.   VIRGINIA PINE  Pinaceae  native tree
 Taxus canadensis Marshall   AMERICAN YEW  Taxaceae  native shrub
 Thuja occidentalis L.   NORTHERN WHITE-CEDAR  Cupressaceae  native tree
 Tsuga canadensis (L.) Carriere   EASTERN HEMLOCK  Pinaceae  native tree


See also these exotic gymnosperms (for fun):


In Summer, 2020 the OSU Ohio Plants course was entirely online (taught remotely). The instructors put together video versions of the lectures that were traditionally done in-person and placed them on YouTube. This material below is an aggregation of those lectures.

The Conifer Life Cycle

Let’s learn some basic botany, as there is an aspect of pine reproduction we find fascinating. It takes two years.

Pollination happens in year one, before the female gametophytes are even in existence. The pollen grains patiently wait for their partners to develop. Amazing!

Unknown Conifer 1
(psst: it’s fir, genus Abies)

Unknown Conifer 2
(psst: it’s yew, genus Taxus)

Unknown Conifer 3
(psst: it’s white-cedar genus Thuja)

Unknown Conifer 4
(psst: it’s hemlock, genus Tsuga)

Unknown Conifer 5
(psst: it’s spruce, genus Picea)

Unknown Conifer 6
(psst: it’s pine, genus Pinus)

Unknown Conifer 7
(psst: it’s red-cedar genus Juniperus)