Cycas-circinalis-cas.. - Cycad Specialist Group

There was a very strong positive correlation between number of leaf scars and C.
circinalis height (Fig. 7). This allowed us to estimate cycad age based on their height.
Given that each individual produces two whorls of leaves per year, the height class
categories in Fig. 4 can be converted to approximate ages, illustrated in Table 5.
Fig. 7. Relationship between height and number of leaf scars for C. circinalis.
N=34, p < 0.001
No. of leaf scars
350
300
250
200
150
100
50
0
y = 0.7832x - 5.9523
R 2 = 0.9505
0 100 200 300 400
Height (cm)
Table 5. Conversion of height classes to age classes based on estimates from
number of leaf scars.
Height class category (cm) Estimated Age Class (years)
Seedlings (no stem)
< 50 (non reproductive) 75
These results suggest that cycads of about 15 years old and more are heavily
harvested for their leaves. The data also indicate that C. circinalis individuals begin to
reproduce at approximately 17 years of age. The biggest individual found measured 330
cm high, and is estimated to be 146 years old.
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