抄録
Plant size and utricle size and maturation at 3 sections on fronds of Codium
fragile were measured bimonthly from February 2011 to April 2012 at
Omaezaki. Plants grew from February to August (reaching mean plant fresh
weight, 142.1 g; plant length, 20.1 cm; diameter of main axis, 8.6 mm) and
remained until December but disappeared completely by February. Utricle
lengths and diameters significantly changed through the study period and
differed among the 3 sections on the fronds in most months. Over the year
monthly mean utricle length and diameter of the basal section ranged
481-662 and 97-212 μm; middle section 707-1046 and 201-304 μm; and apical
section 501-1006 and 118- 320 μm, respectively. Gametangia were confirmed
in the middle section from June to October and apical section from August
to October. In August 2012, utricle size and maturity were compared at 25
sites on one frond. Utricle lengths and diameters were significantly
different among sites and smaller in basal sites. Gametangia were
confirmed from the third branching site from the holdfast to just below
the apical site and more gametangia were found between branching sites
than at the branching sites. Thus the utricle size of C. fragile
changed seasonally and differed among frond sections and
sites.
