Cymose Inflorescence
சயமோஸ் மஞ்சரி
Stop confusing growth patterns. In racemose, the apex grows indefinitely; in cymose, the apex dies as a flower. If you cannot distinguish between apical dominance and floral termination, you will lose marks on morphology.
The idea
In cymose inflorescence, the main axis terminates in a flower. This limits the growth of the axis. Flowers are arranged in a basipetal order, meaning older flowers are at the top and younger buds are at the base. This is the direct opposite of the acropetal succession seen in racemose inflorescence.
Why it matters
This determinate growth pattern allows for a concentrated burst of flowering, which can be an adaptation for specific pollinators.
NEET lens
NEET examiners love the 'basipetal vs. acropetal' comparison. Memorize that cymose = basipetal = limited growth. Expect questions asking to identify diagrams showing floral termination. Do not confuse the order of blooming; always check if the oldest flower is at the apex.
Clinical significance
Biological growth termination is analogous to cellular senescence. Just as the floral meristem stops dividing to form a flower, telomere shortening in human somatic cells limits their proliferative capacity. Both represent a programmed cessation of growth to prioritize reproductive or functional output.
Introduction
Cymose inflorescence has determinate growth — the main axis ends in a flower, and subsequent flowers arise from lateral/axillary buds below. Flowers open centrifugally (center to outside).
Core concept
Types: Monochasial cyme — 1 lateral branch per node. Helicoid (all branches same side — Heliotropium). Scorpioid (branches alternate sides — Begonia, cotton). Dichasial cyme — 2 lateral branches per node (Teak, Calotropis, Bougainvillea). Polychasial cyme — more than 2 branches (Nerium).
Go deeper
Scorpioid cyme (cincinnus) in Heliotropium/Begonia: unrolls as flowers open — resembles a scorpion's tail. Dichasia in Teak — main axis gives 2 equal branches repeatedly.
From Class 10
Racemose inflorescence grows from base upward. Cymose is the opposite — the main axis terminates in a flower and new growth comes from lateral buds.