Field of Science

Gemmae Cups

These cups are located at the apex of the leafy moss and function in reproduction. The moss makes little discs of plant tissue inside the cups called gemmae. These gemmae are moved away from the parental plant via a splash-cup dispersal mechanism. It sounds high tech, but really is just using the power of rain. When rain droplets land in the cup the gemmae are dislodged and can be carried in the water as it splatters away from the moss plant. The gemmae may not be dispersed very far, but it is far enough that this structure is advantageous for the plant to have. This is a from of asexual or clonal reproduction. The plant has made a mini copy of itself that can grow into a new moss plant.

The cups are a common and easily recognized feature of the moss genus Tetraphis
. There are two species that can be found in North America, Tetraphis geniculata and Tetraphis
pellucida. Tetraphis geniculata is rare and grows in limited northern areas on both coasts of North America. It comes as far south as New Hampshire, but has not been sited in Connecticut. The image I have shown is of Tetraphis pellucida (once again taken at the Goodwin State Forest). This species is widespread across temperate areas of North America and is quite common in Connecticut. It grows most commonly on rotten tree parts (logs or branches) on the forest floor. Its common name is the Four-Toothed Moss.

11 comments:

  1. in what class of bryophyte division do you observe gemmae cup formation?

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    1. This genus (Tetraphis), which produces gemmae cups, is located in the class Tetraphidopsida. Does that answer your question? Or did you have a broader question in mind?

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    2. bryophytes dont have gemma cups? they have leafy like structure gemma cups only appear in liverworts.




      By: Ivan XD

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  2. I thought mosses do not possess gemmae, as it's a special feature for liverworts.

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  3. Mosses and liverworts both have gemmae. The gemmae in the moss Tetraphis is similar to the gemmae in Marchantia, in that they are both formed in cups that facilitate the spread of the gemmae by drops of rainwater splashing into the cups. Moss gemmae can also occur at the tips of the leaves, as in the genus Calymperes. They are short filaments of cells that act as the dispersal unit.

    Some illustrations of mosses with gemmae
    Tetraphis - http://www.efloras.org/object_page.aspx?object_id=85661&flora_id=1
    Calymperes - http://www.efloras.org/object_page.aspx?object_id=85403&flora_id=1

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  4. Dear Jessica, would you have some references paper where they described gemmae and gemmae cups in mosses ?
    Thank you very much for your help

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    Replies
    1. I don't know of any research publications that study gemmae cups. One reference that might describe gemmae and gemmae cups is Howard Crum's Structural Diversity of Bryophytes. This book covers lots of developmental and structural aspects of bryophytes and I bet it covers gemmae too.

      The other place you might look are in floras such as the Bryophyte Flora of North America. If a species has gemmae they will describe and probably illustrate them when they talk about the species.

      Good luck finding additional information!

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  5. hello. i wanna ask something. what are the conditions that encourage the liverwort to produce gemmae cup? is it because of the presence of the rain?

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  6. hello. i wanna ask something. what are the conditions that encourage the liverwort to produce gemmae cup? is it because of the presence of the rain?

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    Replies
    1. Hi Nur - Unfortunately I am not sure the stimulus that influences the production of gemmae in liverworts. I think that this could be a great question to ask to the professional bryologists through BryoNet a listserve administered by the International Association of Bryologists.

      You can message the listserve at and read more about the group here

      Best - Jessica





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  7. Its a great pleasure reading your post.Its full of information I am looking for and I love to post a comment that "The content of your post is awesome" Great work. אירוח ביקב

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