452 FRUITS REPLACED BY OFFSHOOTS. 



venti) has a grain 1'2 mm. long, S mm. broad, and weighs "05 grm.; the fruit of the 

 Seychelles Palm (Lodoicea Sechellarum) measures 32 cm. by 18-25 cm. by 22 cm., 

 and weighs 4200-4800 grams. The largest fruits are produced by the Cucurbitacese ; 

 in a suitable soil Gourds attain a diameter of half a metre, whilst fruits of the 

 Melon-pumpkin {Cucurbita maxima) have a greatest diameter of over a metre, and 

 a weight of 75 to 100 kilograms. The fruits of the Bottle-gourd (Lagenaria) attain 

 under favourable circumstances a diameter of 30 cm. and a length of a metre and 

 a half. 



3. CHANGE IN REPEODUCTIVE METHODS. 



Fruits replaced by Offshoots. — Parthenogenesis. — Heteromorphism and Alternation of Generations. 



FRUITS REPLACED BY OFFSHOOTS. 



By Annual Plants are understood such as germinate, grow, and conclude their 

 flowering and fruiting within the limits of a single year, and after the ripening of 

 their seeds die away. The activity of these plants is concentrated on the production 

 of a large amount of seed; it is worthy of note that autogamy is frequently met 

 with amongst them, followed by good results. They produce just so many foliage- 

 leaves as are necessary to provide the materials for their flowers and fruits, and 

 reserve-substances for their seeds. With the production of seed, the leaves, stems, 

 and roots perish without forming vegetative buds or ofishoots, so that these plants 

 are represented for several months by their seed only. Their rejuvenescence can 

 only occur under favourable climatic conditions where an unimpeded germination 

 is allowed these seeds, and when no interference in the process of development is 

 imposed by men or animals. If the weather be unfavourable in the situations 

 where the plants have established themselves, if the summer be a cold one, so that 

 fruit cannot be ripened, they do not perish at the end of the first year, but prolong 

 their existence till another year by means of offshoots, becoming, for the time being, 

 perennial plants. We may put it, in a manner of speaking, that when the danger 

 of extinction threatens, fruit-production is replaced by oflTshoots; instead of fruits, 

 tubers, buds, or other shoots are produced, and not infrequently these structures 

 arise in the position usually occupied b}^ fruits. Among the Crassulacese there are 

 several annual species {Sedum annuum, glaucum, &c.) which normally die away so 

 soon as their seeds have ripened and been dispersed. But when it happens from any 

 cause — as by the premature on-coming of winter — that these processes are interfered 

 with, little rosettes of leaves arise from the base of the stem in close proximity to 

 the root; these are detached, and, as offshoots, continue the life of the plant into 

 another season. Similar phenomena are observed in many other herbs whose 

 flowers or fruit are destroyed by frost. Indeed by experiment these statements 

 can be readily verified. Members of various families (Poa annua, Senecio nehro- 



