Botryoglossum farlowianum is far and away one of the most beautiful of the red algae. It is a deep red, with an iridescent shine that attracts the eye, either under water or on the beach. It is generally between 10 and 40 cm. tall, with thalli 3-9 cm. across.
The holdfast of B. farlowianum is usually rather small, from 1-4 inches in length. It often has other algae growing within it also. The holdfast generally attaches the rock, though sometimes it attaches epiphytically to other algae. To see a close-up of a hold-fast, click here.
The thallus of B. farlowianum is narrow and branched, with a ribbon-like base. It is subdichotomously divided into ribbon-like segments. The basal portion of the branches have a conspicuous midrib, which forks longitudinally into veins, becoming microscopic near the apices.
The midrib is evident in the stipe, and then branches into the various blades.
Here you can see the veins dividing. Notice the pseudoparenchymatous construction of the tissue. Each filament is surrounded by many cells growing out parenchymatously, as in the boxes.
The vegetative cells grow pseudoparenchymatously, in filaments of growth that are then surrounded by "parenchyma" cells. These cells are from a stipe.
As a Rhodophyta, the cells of B. farlowianum have pit connections in their septa. These form during cell growth through mitosis.
The common name, Grape Tongue, refers to the clusters of sori which abound along the edges of the tongue-like thallus. These clusters can be tetrasporangia (containing tetraspores) or gametangia (containing gametes).
Both of these occur along the edge of the blade (marginal proliferations, shown by the black arrow), sometimes extending onto the thallus from the proliferations. Tetrasporangia may also occur in small rosettes on the thallus, shown by the blue arrow.
This proliferation is a tetrasporangia.