Pine Seeds Epidermis
Is a pine cone a seed or a seed coat that contains seeds
inside? Our Pre-k students would like to know.
Actually, it's neither. Here is a very technical answer, to be followed
by a simpler one:
A pine cone is a complex structure that contains either microsporangia
(if it is a male cone) or megasporangia (if it is a female cone). These
sporangia produce spores, which develop into gametophytes. The
microsporangia produce microspores, which develop into pollen grains
(technically called microgametophytes); the megasporangia produce
megaspores, which develop into the structures we call "pine nuts"
(technically megagametophytes). Fertilization happens when pollen
grains are ensnared by megagametophytes and release their sperm. The
resulting embryo then develops inside the megagametophyte (carefully
split open a pine nut lengthwise sometime... you'll see it in there).
Eventually, the embryo will absorb the entire megagametophyte and it
will be covered by a thin, papery membrane. This is a seed - a young
embryo surrounded by a seed coat. All of this happens inside the female
pine cone; it takes about 3 years in pines. Finally, when the seeds are
mature, the pine cone opens and the seeds are released, most of them
immediately becoming squirrel food.
Here's a simpler answer: a pine cone is a structure that makes seeds,
including the seed coat.
Actually pine trees are known as gymnosperms, or having naked seeds. The
prefix gymno- means "naked" in Greek. It is from the same root as gymnasium
and gymnastics because the ancient Greeks competed/worked out naked!
Anyway-seeds for the pine trees are found on the outside of the segments of
a cone. As it opens it puts tension on the segments and the seeds pop off
and fall to the ground. The other type of plant is called an
angiosperm-which means "vessel seed" because the seeds are found inside a
The seeds are inside of the pine cone.
Anthony Brach Ph.D.
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Update: June 2012