Morphology of Flowering Plants

Morphology is the study of the external form and features of plants. You will study tap, fibrous and adventitious roots, the regions of the root tip, and root modifications such as storage roots in carrot and sweet potato, prop roots in banyan, stilt roots in maize and sugarcane, and pneumatophores in Rhizophora. Stem modifications include underground storage stems like the potato tuber, ginger rhizome and Colocasia corm, stem tendrils, thorns, the flattened stems of Opuntia, and runners, stolons, offsets and suckers for propagation. You will learn the parts of a leaf, venation, simple and compound leaves, phyllotaxy, and leaf modifications such as tendrils in pea, spines in cactus and the pitcher of insectivorous plants. The chapter then explains racemose and cymose inflorescences, and the parts of a flower: symmetry, ovary position (hypogynous, perigynous and epigynous), aestivation, the arrangement of stamens and placentation. It ends with fruits, dicot and monocot seeds, how to write a floral formula, and a semi-technical description of a flowering plant, practised with families such as Fabaceae, Solanaceae and Liliaceae.

Detailed Worksheet: Morphology of Flowering Plants Section A - Definitions (10 marks) 1. Distinguish between tap roots and adventitious roots with examples. (2 marks) 2. What are pneumatophores? Where are they found? (2 marks) 3. What is phyllotaxy? Name its three types with examples. (2 marks) 4. Distinguish between racemose and cymose inflorescences. (2 marks) 5. What is placentation? Give two types with examples. (2 marks) Section B - Calculations and Applications (15 marks) 6. A pea flower has 5 sepals united, 5 petals (one standard, two wings and two fused keel petals), 10 stamens (9 fused and 1 free) and a single superior carpel. Write its floral formula in the form K, C, A, G, using brackets for fusion. Name the arrangement of the stamens. (3 marks) 7. A student counted the leaves on a stem of Alstonia: there were 4 nodes with 4 leaves at each node. Calculate the total number of leaves and name the phyllotaxy. If a guava twig with 6 nodes has opposite phyllotaxy, how many leaves does it have? (3 marks) 8. Identify the type of modification in each and its function: potato, ginger, Colocasia, carrot, banyan, Opuntia. (3 marks) 9. A brinjal flower is bisexual, actinomorphic and has 5 united sepals, 5 united petals, 5 epipetalous stamens and a bicarpellary syncarpous superior ovary. Write its floral formula and name the family. What is meant by epipetalous? (3 marks) 10. Classify the following on the basis of the position of the ovary: mustard, china rose, rose, plum, guava, cucumber. Explain how you decided. (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram of the regions of a root tip. (4 marks) 12. Draw labelled diagrams of the different types of aestivation: valvate, twisted, imbricate and vexillary. (3 marks) 13. Draw a labelled diagram of the structure of a monocot seed (maize). (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. 'Stems are modified to perform functions other than support.' Explain with examples of underground stems, tendrils, thorns and propagation structures. (5 marks) 15. Compare the structure of a dicot seed (bean) and a monocot seed (maize) with labelled diagrams. (5 marks) 16. Explain the different types of placentation with labelled diagrams and examples. How is placentation related to the arrangement of ovules in the ovary? (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw diagrams neatly with labels. Write floral formulae carefully, using brackets for fusion.