FLOWERS AND THEIR WORK. 249 



QUESTIONS ON CHAPTER IX. 



1. What is the usual function performed by the various parts of the 

 flower ? Have you observed any cases in which functions other than 

 the usual ones are performed by floral structures ? Show by several 

 examples that the division of the flower into four whorls cannot always 

 be rigidly maintained. 



2. Give an account of the structure and function of a pollen-grain. 



3. Describe the processes which lead to the conversion of an ovule 

 into a seed, and state what is the difference between albuminous 

 (endospermic) and exalbuminous (non-endospermic) seeds, giving 

 examples. 



4. Describe the situation in which honey is produced in any three 

 flowers you have examined. How does it profit a plant to expend its 

 substance in the production of honey ? How is it that some plants 

 dispense with the production of honey ? Name three such plants. 



5. Draw the flowers of any three of the following : Figwort, Snap- 

 dragon, Foxglove, Salvia, Monkshood, Sweet Pea, Dead-nettle. What 

 do you know of the method of pollination in the flowers you draw ? 

 Explain the connection, if any, between the methods of pollination and 

 the time of year at which the flowers appear. 



6. Mention a flower which is naturally self -fertilised, and another 

 which is naturally cross-fertilised. What could you do to aid cross- 

 fertilisation in the first, and self -fertilisation in the second case ? Is 

 the seed produced by cross-fertilisation better or worse than that 

 produced by self -fertilisation ? 



7. Briefly describe, giving examples, the following forms of inflor- 

 escence, and point out the relationship which exists between them : 

 spike, spadix, raceme, head, panicle, umbel. 



8. State what is the essential difference between definite and indefi- 

 nite inflorescences, describing, with examples, the principal varieties 

 of each (definite = cymose, indefinite = racemose). 



9. What is meant by a floral receptacle? What part does it play in 

 our conception of the structure of the flower ? 



10. Name any plants you know in which the flowers are massed in 

 close, flat-topped inflorescences, and mention the advantages which you 

 suppose are obtained by such an arrangement. Name any natural 

 orders that are characterised by this type of inflorescence, and describe, 

 with instances, the differentiation (modification) which the marginal 

 flowers may undergo. 



11. What flowers have you yourself observed being visited by wasps, 

 by butterflies, by flies ? What insects have you j^ourself seen at Sweet 

 Pea, Primrose, Buttercup? Supplement this answer by information 

 obtained in other ways, but distinguish carefully between observations 

 and theories, facts and expectations. 



