meristematic cell and child terms: meristemoid/initial cell

[planteome-user]

Right now there is overlap between the terms meristermoid (PO:0000070) and initial cell (PO:0004011), and as a result, stomatal guard cell has develops from relations to both epidermal initial and meristemoid.

Although an initial cell is now defined as "a cell in a meristem...", in fact, neither child of initial cell (cambial initial or epidermal initial) is part of a meristem. Perhaps it would be better if initial cell was child of meristemoid.

Current definitions: meristematic cell: A cell synthesizing protoplasm and producing new cells by division and with only a primary cell wall. is_a plant cell, part_of meristem

meristemoid: A cell or a group of cells constituting an active locus of meristematic activity in a tissue composed of somewhat older, differentiating cells. is_a plant cell

initial cell: Cell in a meristem that by division gives rise to two cells one of which remains in the meristem, the other is added to the plant body. is_a meristematic cell. is_a meristematic cell

epidermal initial: A relatively unspecialized cell that will give rise to specialized cell types of the epidermis. is_a intial cell

Suggested definitions:

meristematic cell: okay as is, but change from part_of meristem to meristem has_part meristematic cell (since not all meristematic cells are part of a meristem -- we can discuss this)

meristemoid: A meristematic cell that is part of a portion of tissue that is composed mostly of somewhat older, differentiating cells.

initial cell: A meristemoid that by (uneven?) division gives rise to two cells, one of which remains meristematic, while the other is added to the plant body.

epidermal initial: An initial cell that is part of an epidermis and will give rise to specialized cell types of the epidermis.

New term: stomatal initial/stomatal meristemoid (child of initial cell): see separate tracker item: https://sourceforge.net/tracker/index.php?func=detail&aid=3112108&group_id=76834&atid=835555

Reported by: rlwalls2008

Original Ticket: obo/plant-ontology-po-term-requests/272