Lessoniacea Family of Kelps

Southern Sea Palm, Eisenia arborea. A representative of the Lessoniacea Family of Kelps.

Phylogeny:  Lessoniaceae Kelps are a member of the Lessoniacdea Family of Kelps and are in the Phylum Ochrophyta. The name Ochrophyte refers to the ochre color that they display. They are a type of brown algae that, along with diatoms, golden algae, and yellow-green algae.   They are in the Class Phaeophyceae and the Order Llaminariales. Note:  Plants, marine plants included, do not lend themselves to the classic taxonomic groupings that animals do. Some botanists use a function-based system of classification rather than a strictly taxonomic system. Because the rest of this website uses the standard taxonomic based system, we will continue to use that system here. Technically, most marine plants are not plants. Algae, including kelps, historically have been placed in the Kingdom Plantae but they have recently been moved into in the Kingdom Chromista. In the early 1980s the classification of botanical species was divided into three groups – chromists, fungi and plants. Chromists may be tiny unicellular organisms, like diatoms and other plankton, or they may be multicellular such as very large kelps that are characterized by the presence of cilia (hair-like organelles that beat rhythmically to provide propulsion). In chromists, one of the cilium of unicellular species, and the sex cells of multicellular species, is hairy. Yes, the hair-like structure is hairy. I don’t make this stuff up, blame the botanists. These hairs appear like Christmas tree tinsel, and are known as tinsel type cilum. The second defining characteristic of chromists is an additional membrane around their plastids (internal structures responsible for functions such as photosynthesis or food storage).

Distribution:  The Lessoniaceae Kelps are found worldwide, in all subtropical to polar seas. There are thirty-three species in the Lessoniaceae Family of which six are found along the Pacific Coast of Mexico. They are found attached to hard substrates and are found from the intertidal zone to depths that exceed 30 m (100 feet). Ochrophytes may be found anywhere there is free standing water, including freshwater, marine and terrestrial habitats. Because they rely on sunlight for photosynthesis, they will only survive with access to adequate sunlight.

Morphlogy: Lessoniacea Kelps are multicellular, large, and contain unique pigments, glucose polymers, and plastids that contain carotene, Chlorophyll a and Chlorophyll c. They have a holdfast, which anchors the plant to the substrate, a stalk, and a blade (leaf) where photosynthesis occurs. They may reach 45 m (148 feet) in length, and may grow up to 61 cm (2 feet 0 inches) per day.

Ecosystem Roles: Kelps are critical components of healthy marine ecosystems. They provide food and habitat for numerous other species.

Reproduction:  Brown algae alternate generations between two free-living life phases. The first phase is a large, diploid sporophyte stage and the second is a microscopic haploid gamophyte stage.Their blades divide during early sporophytic (when a haploid sperm fertilizes a haploid egg) development.