Lphioglossum (adder's-tongue) is a genus of about 25-30 species of Ophioglossales in the family Ophioglossaceae, with a cosmopolitan but primarily tropical and subtropical distribution. The name Ophioglossum comes from the Greek, and means "snake-tongue". Adders-tongues are so-called because the spore-bearing stalk is thought to resemble a snake's tongue. Each plant typically sends up a small, undivided leaf blade with netted venation, and the spore stalk forks from the leaf stalk, terminating in sporangia which are partially concealed within a structure with slitted sides.

Adderstongue

Lphioglossum (adder's-tongue) is a genus of about 25-30 species of Ophioglossales in the family Ophioglossaceae,…

An illustration of a fertile branch of horsetail and spore of equisetum with unrolled elaters.

Horsetail

An illustration of a fertile branch of horsetail and spore of equisetum with unrolled elaters.

Cone of horsetail.

Cone of horsetail

Cone of horsetail.

An illustration of a flowering branch of common mare's tail; a, flower before athesis; b, flower after athesis; c, fruit. The Common Mare's tail, Hippuris vulgaris, is a common aquatic plant of Eurasia and North America. The species is also sometimes called Horsetail, a name which is better reserved to the Horsetails of genus Equisetum. These are unrelated to the water plant, though there is some resemblance in appearance.

Common Mare's Tail

An illustration of a flowering branch of common mare's tail; a, flower before athesis; b, flower after…