Thursday, December 30, 2010

Intimate anatomy of giant horsetail

Giant horsetail or Great horsetail, Equisetum telmateia is a somewhat atypical fern, very primitive, with some structures, both macroscopic and microscopic have changed very little in many millions of years and still remember the primitive algae that evolved, colonizing the land firm from the sea. It has an underground rhizome in spring flows two ways of stems: the highly branched sterile, long and with chlorophyll and unbranched fertile, much shorter, without chlorophyll, which develop before the sterile and end up in a structure called a strobilus, where spores are formed within the sporangia distributed in the form of honeycomb.

Sterile stems of Equisetum telmateia in May, on the outskirts of the city of Horta on Faial Island in the Azores Archipelago.

Sterile stems of vigorous Equisetum telmateia in November, in bed Torrent Major of Soller Valley on the Island of Mallorca.

Sterile stem of Equisetum telmateia with branched internodes.
Detail of internode of a sterile stem of giant horsetail.

Strobilus of a fertile stem, with the sporangiophores in the form of honeycomb cells, each of which with several sporangia and spore-filled sacs on the inside.

Strobilus detailed above, with the sporangiophores to be separated as they mature and reveal the green sporangia filled with spores.

Cross section of a strobilus with the interior of the stem that is empty and around the sporangiophores with sporangia directed inward. (Double click on the picture to enlarge)

Sporangia in the form of sacks of green spores and begin its spread, tearing the thin membrane that contains them and so the wind can drag away.

Mature spores of Equisetum telmateia bags out of the sporangia to start the adventure of a lifetime. The spores can be male or female. When germinating produce male and female gametophytes and in turn they produce male and female gametes. After fertilization of the oosphere of a female gametophyte by antherozoids of a male gametophyte, is born a new Equisetum telmateia. (Double click on the picture to enlarge)

The spores have 4 elaters, which are as expansions in the form of belts, which act like the blades of a helicopter and, aided by the wind carry the spores as far as possible to colonize new territories.

Two Equisetum telmateia spores that have a fairly large and at first light green color that changes to brown over time.

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