SOME OBSERVATIONS ON CYOAS IN LAHORE. 119
year and still older ones produce clusters every other year or even at longer intervals. It may be mentioned also that it is difficult to give the exact age of the plants as the time during which the buds had remained attached to the parent plants is not known.
Another series of observations was undertaken on four large plants growing in the Botanic Garden. These are certainly more than twenty years old at the least. All of them produced cones in May 1919, and the following measurements were taken in October 1919. The girth is about the same throughout the whole length of the stem except at the very base where it is a little smaller.
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The trees were kept under observation from October 1918 to November, 1920. The following was the sequence in which the foliage leaves and sporophylls were arranged with the time of appearance where known:—
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The number of foliage leaves in each cluster was usually about sixty, and the number of sporophylls in each cluster varied between 120 and 170. It will be seen that there is no invariable alternation between the foliage leaves and the sporophylls though in many cases it is distinctly present. Again a cluster of foliage leaves appears usually after about eighteen months, though a cluster of sporophylls appears before the second foliage cluster in the meantime. We can say that usually one cluster appears every year whether of foliage leaves or sporophylls. Plant No. 2, however is very curious in this respect. It produced a cluster of foliage leaves in April and immediately after that a cluster of sporophylls about the end of May. Even now its activity was not quite exhausted and it produced another cluster of foliage leaves in November, 1920 when the other three trees showed no sign of forming any leaves. This behaviour is quite unusual but the cause of this excessive activity is not known.
In No. 4 three clusters of green leaves were visible below the cone, but in the others only two such clusters were present. The leaves below them had all died and therefore been cut away. On the
