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.

抄録全体を表示