The sporophores of this species first appear at the time when the buds of the host are beginning to swell; in Southland, in 1946, when most of the investigation was carried out, this occurred during the first week of September. Spore shedding starts early in October and reaches a peak towards the end of November. The first fructifications seen were growing from small twigs showing, little or no sign of gall formation; large galls produce fructifications later.

The galls are small in proportion to the diameter of the branch or stem, as compared with those of C. nigra; they usually occupy about two-thirds of the circumference of the branch and are flattened slightly at the point of origin. When a branch is completely girdled the upper part may die, in which case the death of the gall may follow. In contrast to C. nigra, galls on the main stem take the. form of rope-like encircling bands.. for example one sapling of 11 in d.b.h. had three galls, at 3ft, 4ft 2in. and 5ft 6in from the ground. The lowest was 2 in high and 12 in in circumference, leaving 1 in of bark unaffected, the middle gall was 12 in high and 10 in in circumference, and the highest was 1 1/2 in high and 11 in in circumference. The last two galls cornpletely encircled the stem. See Plate 12 C.

The surface of the gall appears smooth, but if the bark is removed the wood is found to be very uneven, being contorted and produced into sharp spines, the tips of which split into fibres which penetrate through the bark. It is from these points that the stromata develop. The scar left on the gall when the fructification falls is a white circular spot, with, in many cases, the remains of the central tube of fibres which pulls out of the stroma.