CONTENTS xi 



PAGE 



or central placentation. Dissepiments or septa — true and 

 spurious or false. Replum. Free central placentation. Super- 

 ficial placentation. Ovule or macrosporangium, parts of- — 

 nucellus, funicle, integuments, micropyle, chalaza, erabryo- 

 sac, oosphere or female cell. Ovules, classes of — ortho- or 

 a-tropous, anatropous with raphe, campylotropous. Ovules, 

 positions of — erect, suspended, pendulous, ascending, horizontal. 

 Flowers, isomerous or anisomerous — dimerous, trimerous, tetra- 

 merous, or pentamerous. Flowers — symmetrical or asym- 

 metrical. Symmetrical flowers — zygomorphic or mono-symmetri- 

 cal, actinomorphic or poly-symmetrical. Floral diagrams — the 

 posterior and the anterior part, median lateral and diagonal 

 planes, empirical or theoretical diagram. Floral formute 91 



Chapter XV— POLLINATION 



Pollination — autogamy or self-pollination, allogamy or cross -pol- 

 lination. Flowers classified according to the nature of their 

 pollination — (i) unisexual, (2) dichogamous, (3) homogamous 

 and herkogamous, (4) dimorphic or heterostylic, trimorphic, (5) 

 cleistogamous, (6) self-pollinated. Examples of unisexual, 

 dichogamous, herkogamous, dimorphic, cleistogamous and 

 homogamous flowers - lo5 



Chapter XVI— FLOWERS IN RELATION TO 

 POLLINATING AGENTS 



Flowers according to agency of pollination — (l) anemophilous or 

 wind-flowers, (2) entomophilous or insect-flowers, (3) aquaphilous 

 or water-flowers. Character and examples of — wind-flowers, 

 insect- flowers, and water-flowers - . - 114 



Chapter XVII— ENTOMOPHILOUS FLOWERS 



Entomophilous flowers divided into nine classes — (l) pollen-flowers, 

 (2) flowers with exposed nectar, (3) flowers with partially con- 

 cealed nectar, (4) flowers with completely concealed nectar, (5) 

 social flowers with concealed nectar, (6) bee-flowers, (7) butterfly- 

 and moth-flowers, (8) pit-fall flowers, (9) pinch-trap flowers. 

 Character and examples of— (l), (2), (3), {4), (5), (6), (7), (8), (9). 

 Highly specialized insects' preference for highly specialized 

 flowers. A series of colours constructed in order of their pre- 

 ference by bees. Colours preferred by butterflies 124 



Chapter XVIII— STRUCTURE OF POLLEN-GRAINS 



AND OF OVULES. FERTILIZATION AND 



FORMATION OF SEEDS 



Fertilization. Development of the contents of the embryo-sac before 

 fertilization — egg-apparatus, antipodal cells, secondary nucleus of 

 the embryo-sac, synergidse. Structure of the pollen -grain — 



