Cladophyll temperature was maintained at 25 [degrees] C with thermoelectric coolers, and water vapor pressure deficit (VPD) was generally held between 1.2 and 1.7 kPa.
Effect of cladophyll age on photosynthetic parameters was analyzed by Tukey's test.
In the rapidly expanding cladophyll tissue measured in January, the two cultivars exhibited similar values of A throughout the day, whereas in the fully expanded cladophyll tissue measured in February, a significant difference in A between the two cultivars was observed throughout the measuring period.
For each fern, mean values of cladophyll length (l) and diameter (d) were determined with calipers and a stereomicroscope with a graduated eyepiece.
Mean cladophyll diameter, and the ratio of cladophyll volume/cladophyll area, were positively associated with [A.sub.sat] in both young and older plants (Table 4).
Mean cladophyll diameter, ratio of cladophyll volume: cladophyll area (V:A), and mean fern nitrogen concentration, chlorophyll concentration (Chl), soluble sugar concentration (SSC) and soluble protein concentration (SPC) expressed per unit of cladophyll volume, and [A.sub.sat] per unit of dry weight ([A.sub.sat] [DW]), for ferns from 6-yr-old field plants (n = 21) and 10-mo-old glasshouse plants (n = 10) of three cultivars.
The fern is extremely hardy and can survive for decades without much attention, but while the berries cause diarrhea and vomiting if consumed, and are deadly to cats and dogs, the newly emerging cladophylls
are leaflike, succulent stems modified for water storage.