Monterey Bay Aquarium Research Institute
Marine Botany

Botryocladia pseudodichotoma
Marc Felton

Botryocladia drawing

Range: Vancouver - Baja Calif. depth: 6-18 (38) m.

Table of Contents

The Sea Grape

Commonly known as "sea grapes," Botryocladia (botryo=grape, cladia=branches) pseudodichotoma is an abundant member of the RHODOPHYTA (red algae). The following phylogeny consists of links to list of common characteristics which justify Botryocladia's inclusion:





genus Botryocladia


  • thallus is 10-30 cm. tall
  • elongate, pyriform (pear-shaped), sacchate (sack-like) branches
  • sacchate branches are 4-7 cm long and 6-25 mm in diameter
  • branches contain a colorless, acidic, polysaccharide and protein mucilage which makes them bouyant and therefore better able to compete for light
  • 3 cell layers
    1. pigmented cortical cells
    2. unpigmented medium sized gelatinous cells
    3. unpigmented large gelatinous medullar cells (& specialized secretory cells)

Secretory Cells

secretory cells cells under microscopeThese gland cells cluster in groups of 10-20 on the inward facing surface of medullar cells which in pseudodichotoma are noticeably smaller than its neighbors. It is easy to view secretory cells under a microscope by making cross-sections with a razorblade.

Life History

life history of Botryocladia

As with all Florideophyceae, B.pseudodichotoma has a tri-phasic life history.

tetrad of spores Cortical cells of the diploid tetrasporophyte undergo meiosis to create cruciate tetraspores (3.88 million/day). Each of the 4 spores can grow into a haploid gametophyte (male or female).

carposporophyte A mature male gametophyte emits spermatia which fertilize cells on the female gametophyte. Where fertilization has succeeded, a diploid carposporophyte grows on the female gametophyte.

hole in cystocarp Each carposporophyte has a pore opening to the outside through which it releases diploid carpospores. These carpospores settle and grow into tetrasporophytes.

Botryocladia bibliography