(A) Habit (B) Coralloid roots (C) Green leaf (D) Young Green leaf
Figure 15.8 Cycas
Cycas has dimorphic leaves, (i.e.,
two types of leaves): scale leaves and green leaves. Both
develop spirally around the stem apex. The spirals of scale leaves alternate
with those of green leaves. The scale leaves are small and non-green.
The green photosynthetic leaves are between 1-3 meters long and unipinnately
compound (Fig. 15.8 C and D). They form a crown around the stem apex.
Young leaves show circinnate venation (similar to ferns). Each
green leaf has a strong petiole and a main rachis with two rows of numerous
leaflets (pinnae). Each pinna is long, linear and lanceolate with an entire
margin. It has a distinct midrib but lateral veins are absent. Some of
the basal leaflets are reduced to spines.