Phaeophyta - Brown Algae-9
Phaeophyta - Brown Algae-9
Sexual Reproduction - Laminariales
These large organisms and their relatives are called Kelps.
They can form Kelp Forests which occur on the west coast of the USA & Canada. These are very important Marine Ecosystems.
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| Sporophytes of Macrocystis sp. | Top of a Bull Kelp |
The Haploid Gametophytes are MICROSCOPIC.
The Female Gametophyte has Large Cells and is Sparsely Branched.
One Egg is produced by each Oogonium.
It is Extruded to the Outside but NOT Released
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 Gametophytes of Laminarians |
The Male Gametophyte is Highly Branched.
Motile Sperm are produced (One/Antheridium)
Fertilization -> Cell Divisions -> Embryonic Sporophyte
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 Young Sporophytes |
The Mature Sporophyte produces Unilocular
Meiosporangia which produce
Motile Meiospores.
 Microscopic view of the Meiosporangia which develop on the Laminae of Mature Laminarians |
 Part of a Lamina from a Mature Sporophyte |
These Settle, and synthesize a Cell Wall that cements them to the substrate. These become the large Diploid Sporophytes.
This life cycle has a Heteromorphic Alternation of Generations because the Gametophyte Plants are minute and simplistic compared to the Large Complex Sporophytes.
It also displays Oogamy as the Egg is larger than the Sperm.
 Bull Kelp Nereocystis luetkeana Forest |
 Giant Kelp (Macrocystis pyrifera) |
