(B) Dicotyledons

Hibiscus rosa-sinensis (China rose)

This is one of the most common members of the dicotyledons and shows all the typical characteristics of the group. It is widely cultivated as a garden plant.

The life cycle of China-rose is predominantly sporophytic and shows meteromorphic alternation of generations.

a) Plant Body - External morphology (Fig. 15.16)

The plant body of the Chinarose is a diploid sporophyte. It is an erect, evergreen perennial shrub, about 6-8 feet tall. The plant is differentiated into roots, stem and leaves.

The roots form a branched tap root system at the base of the stem. It is an efficient anchoring and absorbing organ.

The stem is erect, hard (woody) and cylindrical with a rough surface. Lateral branches develop in acropetal order. Branching of the stem is alternate.

Leaves develop on the stem at the nodes in an alternate arrangement. Each leaf is simple and has two free lateral stipules at the base. The leaf lamina is entire, ovate with acute apex and serrate margins. Venation is branched or divergent. Leaves are dorsoventral and deep green. The surface is covered with multicellular epidermal hairs.

b) Inflorescence: In Hibiscus rosa-sinensis, the inflorescence is a single flower. The inflorescence axis develops in the axil of a leaf and bears a single terminal flower (Fig. 15.16). The joint (articulation) between the axis and the pedicel is distinctly visible.

• The flower (Fig. 15.16B) is actinomorphic, complete, bisexual, and pentamerous (5-petals). The flower has an epicalyx external to the calyx. An epicalyx is a whorl of 6-7 bracteoles which are small, and green.

• The calyx consists of five green sepals.

• Corolla. Polypetalous (5-petals) are fused with the staminal tube at the base. The corolla is red, yellow, white or pink.
  
  

Table of Contents

15.0 - Introduction
15.1 Pteridophyta : General Account
15.2 Gymnosperms
15.3 Angiosperms : Dicotyledons
15.4 Angiosperms : Monocotyledons
15.5 Vascularization
15.6 Development of seed habit
15.7 Development of Flower and Fruit

Chapter 16