grammitid

Grammitid is a family of plants in the fern order Polypodiales. They are commonly known as grammitids or terrestrial grammitidis. These plants are found in tropical regions of the world and are typically epiphytic, meaning they grow on other plants.

Grammitids are known for their small to medium size, usually ranging from 10 to 40 centimeters in diameter. They have a unique characteristic, having paired pinnae, or leaflets, that are linear, lanceolate, or saccate in shape. The veins of the leaves are also notable, exhibiting a parallel vein pattern.

Grammitids reproduce via spores, with the fronds usually bearing sporangia on the underside of the leaves. The spores are light brown, 50 to 65 micrometers in diameter, and ellipsoidal in shape. Gametophytes typically develop on the fertile fronds, first originating as a small cell or germ then developing into a tuberous structure.

The species of grammitid are generally found in tropical regions worldwide, where they occupy shaded, humid environments, such as in forests and on rocks. The plants thrive in areas with moderate humidity, shade, and good air circulation. Grammitids are also often associated with other vascular plants, such as orchids and bromeliads, on which they grow epiphytically. Notable appearances of grammitid can be seen in collectors' lists and in conservation projects regarding tropical epiphytes.