Question

Amphigastria is found in
A. Riccia
B. Marchantia
C. Porella
D. All above

Answer 1

In bryophytes the stems and leaves are important as they make up the gametophyte of the plants. The gametophyte of leafy liverworts or the bryophytes is described as consisting of stems with the leaves.

Complete Solution:
The gametophyte of bryophyte consists of stems and leaves and the sporophyte is a black capsule-like structure present over a stalk. The stems of the gametophyte are branched and there are many different types of branching. However there are two basic ways in which branches can develop that are at the tip of the stems or at some distance behind the tip of the stem.

A typical liverwort has leaves of two different sizes that are arranged in three rows along the stem. The leaves that are present on the lateral side along the opposite side of the stem are called lateral leaves. These types of leaves are larger in size and grow in two rows. Some of the liverworts which grow along some type of substrate such as soil, rock or bark of trees, lateral leaves are parallel to the substrate and on the underside of the stem a third row of leaves are present on the stem. These are often referred to as under leaves. The underside of the liverwort is also known as the ventral side and the leaves covered are known as ventral leaves. These leaves that are present on the ventral side are smaller and do not have mid ribs. These types of leaves are known as amphigastria.

The amphigastria on the ventral surfaces are small leaves which resemble the postical lobes of the dorsal leaves. The amphigastria are much broader with frequently decurrent bases. This condition is found in the gametophyte of Porella, in which the gametophyte is flat, dorsiventral and foliose type. The stem or the axis is branched and bears three rows of leaves, two dorsal rows and one ventral row. Lateral leaves are present on the dorsal rows and leaves of the ventral are called amphigastria.

Therefore, the option C is the correct and most appropriate option.

Note: Amphigastria are the types of leaves that are arranged on the ventral surfaces of the leafy liverwort, Porella. In the gametophyte of Porella, they appear in addition to the dorsal leaves and are present in a single layer of leaves.