Nov. 1906.] 



413 



MISCELLANEOUS. 



Lessons in Elementary Botany and Agriculture. 



By J. C. Willis. 



Multiplication of organs, or the presence of more than one in a place where 

 we should expect only one, is not uncommon, especially among stamens, as e.g. in 

 the Malvacea?, Hypericum, &c. 



Abortion, or absence of one or more members from places in which we should 

 expect to find them, is not uncommon. In the Labiatee and allied orders, for instance, 

 there are only four stamens to five petals, and the missing stamen is often present 

 as a staminode or rudiment. 



Change of Form of the Receptacle is a frequent case. In the most primi- 

 tive flowers and in a very large number now existing, the stalk or axis is more or 

 less elongated, the carpels are at the top or superior, and the other organs— stamens, 

 petals, sepals— are below them, in order, or hypogynous. In wild Strawberry, 

 Potentilla, &c, the receptacle is more or less flattened on the top, so as to have a 

 kind of \7 shape in section. 



In a good many plants the flattening is above the calyx and a disc is 

 formed in the flower, but as a more general rule the calyx springs from the 

 margin ; and as a rule also the sides grow so rapidly as to form a hollow 

 cup in which the calyx springs from the edge, the corolla and stamens from 

 the inner slopes, and the carpels from the centre and bottom. As no other organs 

 spring from the top of the carpels, the latter are still termed superior but 

 the other organs are perigynous. (PL III. fig. 17 &c. K = calyx ; = corolla ; 

 A = stamens ; G=carpels.) In yet other cases again the receptacle is so hollowed out 

 as to contain the carpels, and sepals, petals, and stamens spring from it actually 

 above the carpels. In this case they are inferior and the other organs are epigynous. 



These are on the whole the most important points in the structure of a 

 flower, and it is desirable early to become familiar with them. 



Flower, or perianth, calyx, corolla, stamens may be hypo- peri- or epi-gynous (above) the carpels 

 superior or inferior. Perigynous flowers may be sballowly or deeply perigynous. There may be a 

 disc above the calyx in a flower. Sometimes the receptacle elongates between petals and stamens 

 or between stamens and carpels. 



Floral Symmetry is another feature that shows much variety. In many 

 flowers the numbers of members in each whorl are the same, and each is like all the 

 others in the whorl. Such a flower is quite symmetrical or regular. It more fre- 

 quently happens that the symmetry is disturbed by the presence of fewer carpels 

 than other organs, but such a. flower is also called regular. If, however, some of the 

 organs in a whorl are missing, or if they are not all exactly alike, the flower is 

 irregular. Irregularity is most common in the perianth, and the terms used are 

 given below. 



The flower usually stands in the axil of a bract, and the side facing the 

 bract is anterior, the other posterior. 



We must now pass on to deal with the structure of the flower in detail. 



The Bud. — An important point in classification is often the arrangement of 

 the leaves in the bud. If they do not even meet by their edges their aestivation, as it 

 s called, is open, if they meet by the edges, valvate, if they overlap, imbricate. A 

 special case of the last is twisted when each leaf overlaps with one side and uiiderlaps 

 with the other, so that the bud looks tAvisted, 

 54 



