POC Conf. Call 5-03-11

POC meeting, Webex Conference Call; Date: Thursday April 28th, 2011 10am (PDT)

In attendance:

POC members:

Absent:

Collaborators:

Acceptance of the minutes from the POC_Conf._Call_4-28-11?

New terms for Physcomitrella and related taxa (continued)

Plant Tissues

paraphyllium

Tiny filaments, scales or leaf-like structures scattered on the stems of some leafy bryophytes. Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition (MO definition)

Crum defines them as "Small green outgrowths formed between the leaves on stems and branches of some pleurocarps (mosses that produce archegonia and sporophytes laterally, rather than on the tips of their axes) and a very few leafy liverworts."

Schofield describes paraphyllia as outgrowths of the epidermis, but he also describes leaves that way.

Moss Ontology has paraphyllium listed as a plant organ, but they do not arise from the SAM as phyllomes do.

Proposed definition: A portion of epidermal tissue that is a small outgrowth from the epidermis between the leaves of a gametophore axis.

Comment: Paraphyllia are much smaller than leaves and may be filamentous, scale-like, or leaf-like. Found in pleurocarpous mosses and a few leafy liverworts.

is_a epidermis, part_of gametophore axis

The paraphyllia are the small, dark structures between the leaves.

paraphysis

Moss Ontology definition: Sterile, septate, usually uniseriate hairs intermixed with sex organs. Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition

From Parihar: sterile, slender filaments accompanying reproductive organs.

From Schofeld: filamentous sterile structures intermixed with the sex organs of most mosses

These are a kind of trichome

Proposed def.: A slender, usually uniseriate multicellular trichome that grows intermixed with the gametangia.

Comment: Found in bryophytes and pteridophytes, especially in mosses.

adjacent_to gametangium, plural: paraphyses; particpates_in gametophytic phase

axillary hair (PO:0030060)

Moss Ontology definition: A small filament in an axil consisting of one long terminal cell atop a basal stalk (also called club-hair). Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition

This is a type of trichome. Axillary trichomes may also be found in angiosperms, but they are different, so suggest we specify that this for hairs in gametophores.

Proposed def., gametophore axillary hair: A multicellular trichome consisting of one long terminal cell atop a basal stalk that grows in the leaf axil of a non-vascular leaf.

Comment: Found in pleurocarpous mosses. Form in the axils of leaf primordia, and may disappear when the gametophore is mature.

synonym: club-hair; part_of gametophore

rhizoid

Moss Ontology definition: Filamentous tissue protruding from the gametophore stem with a rooting function.

Rhizoids may also grow from thalli. They arise from an epidermal intial (the rhizoid initial), and so are like trichomes. Like trichomes, they may be uni- or multicellular

Proposed def.: A trichome that is part of a plant in the gametophytic phase and has positive gravitropism.

Comment: Found in bryophytes and pteridopytes growing from the epidermis of the lower surface of a gametophore or thallus. May also arise directly from a protonema. May be muticellular or unicellur. Usually serves to anchor the plant to the substrate.

develops_from rhizoid initial, participates_in gametophytic phase

tmema (PO:0030061)

Moss Ontology definition: An abscission cell at the base of a gemma (vegetative propagule). Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition

Their definition defines a cell type, but they have tmema as a tissue type. It would be the tissue composed of tmema cells

Proposed def.: A portion of plant tissue that has as parts tmema cells.

Comment: Found in bryophytes at the base of a gemma. Participates in abscission of the gemma.

participates_in gametophytic phase, has_part tmema cell

antheridium jacket layer (PO:0030053)

Moss Ontology definition: A layer of cells that surrounds the spermatogenous tissue that cannot give rise to sperm.

The term jacket layer is also used for the outer layer of sporangia. Suggest naming this term antheridium wall or antheridium jacket layer

proposed definition: A portion of plant tissue that is a single layer of cells on the outside of an antheridium.

Comment: Cells in the antheridium jacket layer surround the inner spermatogenous cells and do not give rise to sperm cells.

part_of antheridium; synonym: sterile jacket layer, antheridium wall

Parts of sporangium

This is continued from our discussion at the POC_Conf._Call_3-8-11

Moss Ontology has requested the terms archesporium, amphithecium, and endothecium.

For background, see Summary of sporangium development in various non-angiosperm taxa.

Currently classes like exothecium, endothecium, primary parietal cell layer and tapetum are part of anther wall (PO:0000002). However, these layers and their constituent cell types can be part of any sporangium, not just an anther. Proposed making them part of a general class sporangium wall (as we did for parts of leaf). Tissues that are in all sporangia can be a child of this class. We could make specific children for anther exothecium, anther endothecium, etc.