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 slit sides.

[3] When the leaf blade is present, there is not always a spore stalk present, and the plants do not always send up a leaf, sometimes going for a year to a period of years living only under the soil, nourished by association with soil fungi.

[5] The species Ophioglossum reticulatum has the highest number of chromosomes found in any multicellular organism.

& Goswamy O. crotalophoroides Walter (Bulbous adder's tongue) O. parvifolium Hook.