DIVERSITY OF LIFE

SYNOPTIC DESCRIPTION OF THE PHYLUM PRASINOPHYTA

EUKARYA>ARCHAEPLASTIDA>VIRIDIPLANTAE>CHLOROBIONTA>PRASINOPHYTA

The following description came from van den Hoek et al. (1995), Melkonian (1989, 1990), Melkonian and Surek (1995), and Sym and Pienaar (1993).  
I. SYNONYMS: praesinophytes,   
II. NUMBER: >180 species.  

III. PHYLUM CHARACTERISTICS:

A. Structure and Physiology

Cell Form:  Generally, unicells; some (Prasinocladus) are benthic filaments.

Flagella: 1-8 flagella, laterally or apically inserted with sparse hairs or scales and anteriorly directed.

Basal Bodies: Basal bodies with roots that are cross-shaped to unilateral; those with the broad roots have a multilayered structure (MLS) some with rhizoplast and broad flagellar roots, others with flagellar roots associated with the cell surface.

Cell Covering: Usually covered with elaborate scales of cellulose. Some naked.

Chloroplasts: Variable; grass green with chlorophylls a and b, B-carotene and various xanthophylls. Eyespot, when present, is always enclosed within the chloroplast.

Food Reserves: True starch that is deposited within the chloroplast in association with a pyrenoid.

Mitochondria: Plate-like cristae.

Golgi: Present.

Nucleus: Presumed haploid in vegetative forms.

Centrioles: Not present

Inclusions and Ejectile Organelles: Not present.

B. Mitosis, Meiosis and Life History

Mitosis: Variable, open to closed; with or without a persistent phycoplast; cytokinesis by furrowing to cell plate formation.

Meiosis: Present at least in Nephroselmis.

Sexual Reproduction and Life History: Confirmed in only one genus, Nephroselmis, which is isogamous and haplontic.

C. Ecology: Found in marine, brackish, and fresh water.  Free-living and flagellated, or benthic with quadriflagellate zoospores.

 

By Jack R. Holt.  Last revised: 03/19/2013