Anthocerophyta-1

Diversity & Distribution
This is a small group with only 4 - 5 Genera. *The Genus to remember is Anthoceros.* They are Widespread and occur in the Temperate & Tropical zones. They generally grow in wet habitats.	Anthoceros with Prominent, Immature Sporophytes. It should be obvious why these are called "hornworts".

Their Growth Form = Thallose
They are somewhat rounded and are said to be Orbicular. They are Dorsiventral & the Ventral side produces Rhizoids. Stomata have been reported but are not common.! Stomata represent one of the crucial adaptations of terrestrial plants. The basic structure of stomata is identical throughout Vascular Plants.	Anthoceros with Frilly Gametophytes A closer view of the Gametophyte Thallus.
Mucilage Cavities Air Chambers are present and Mucilage cavities are also observed. The mucilage may help to conserve water. Thallus with Cyanobacteria (Dark Protrusions on the far Right-hand side of the Thallus)
SEM Ventral side of Thallus with Openings to the Mucilage Cavities (Look for the small Dark Spots near the "Midrib".) Thalli can contain Endosymbiotic, Nitrogen-Fixing Cyanobacteria! This is an important adaptation! The nitrogen derived from the cyanobacterium has obvious value for the host. Nitrogen is one of the most limiting elements in terrestrial environments. Consequently, plants with N-fixing bacteria can colonize poor sites more readily than other plants. This might allow them to survive in the midst of plants which would otherwise out-compete them for space and sunlight.
I see these plants on newly disturbed sites in the moist forests of Oahu. They could be very important for soil stabilization & enrichment on areas disturbed by pigs or abiotic insults. Their ecological role in disturbance biology in Hawaii deserves some attention.

Unique Chloroplasts are seen in this Taxon

They have extremely large Chloroplasts and each cell may only have one Chloroplast. They also have a Pyrenoid. This is common in Chlorophyta. It could be interesting to compare the Ultrastructure and the Molecular Biology of Anthoceros plastids with those of Green Algae.

Anthoceros cells with solitary, massive Chloroplasts

Unique Chloroplasts are seen in this Taxon
They have extremely large Chloroplasts and each cell may only have one Chloroplast. They also have a Pyrenoid. This is common in Chlorophyta. It could be interesting to compare the Ultrastructure and the Molecular Biology of Anthoceros plastids with those of Green Algae.	Anthoceros cells with solitary, massive Chloroplasts

Their Growth Form = Thallose