Miscellaneous 



414 



[Nov. 1906. 



The Perianth protects the stamens and carpels from exposure before they 

 are ripe, and aids in the attractiveness of the flower to insects. As a rule it is in 

 two whorls, sepals and petals, which are often coherent. 



It may be hypo- peri- or epi-gynous, of |free and distinct organs ( poly-phyllous, -sepalous, -petalous) 

 or of coherent organs (gamo-phy lions -sepalous, gamo or sym-petalous). In the latter case the coherent 

 part or tube bears the free lobes together forming the limb. The perianth may be regular or irregular, 

 sepaloid (looking like a calyx) or petaloid (like a corolla). The sepals are commonly leafy and green, 

 but may be woody as in the blue gum, or brightly coloured as in some Ranunculaceas. In many 

 epigynous flowers they are much reduced. In Compositse, e.g., dandelion or goatweed, they are often 

 represented by a pappus of hairs or bristles. In Malvaceae, some Rosacese, &c, there is an epicalyx 

 of leaves outside the sepals and just like them. The petals are usually of some other colour than 

 green, and of delicate texture. They may be narrowed at the base into a claw, may be bifid 

 (notched into two), &c, spurred (with long hollow projection as in Viola, &c. ). 



The general form of a sympetalous corolla may be tubular, funnel-shaped, belt-shaped, urn- 

 shaped, wheel-shaped. &c. 



The stamens of a flower, taken together are termed its androeceum. A 

 typical stamen consists of a stalk or filament bearing an anther, consisting of two 

 chief lobes united by a prolongation of the stalk {connective). Each lobe usually 

 contains two pollen sacs. 



The stamens may be hypo- peri- or epi-gynous ; epiphyllous, episepalous, epipetalous (adherent to 

 perianth, sepals, petals) ; few, or indefinite (many and variable in number) : monadelphous, diadelphous, 

 polyadelphous (united in 1, -2, many bundles with free anthers) or synandrous (united, including anthers, 

 into one mass). There may be two stamens longer than the rest (didynamous). 



The anther may be sessile or on a filament ; it may be versatile (balanced transversely on the 

 end of the stalk) ; it may dehisce or open by slits, by pores, or otherwise. 



The pollen may be smooth or not, powdery or coherent, &c. ; the grains as in Orchids and 

 Asclepiadaceae may be united into masses or pollinia. 



The carpels of a flower, taken together, form its gynoeceum. The simple leaf- 

 like sporophyll occurs only in ferns, Selaginellas, &c, and in all the higher flowering 

 plants we find the sporophyll folded inward to form a carpel, bearing the ovules 

 (which will later form the seeds) inside. The hollow chamber (or often chambers if 

 the carpels are united) is called the ovary, and the ovules are borne on placentae or 

 cushions. The tip of the carpel is usually prolonged into a more or less thread- 

 like style ending in a (frequently sticky) stigma or receptive organ for the pollen 

 grains. Only a few plants have apocarpous ovaries, (i.e., of free carpels) ; most are 

 syncarpous, (of united carpels), and the arrangement of the placentas becomes of 

 great importance. They may be axile (Plate III, 21) and the ovary be multilocular 

 or many-chambered, the number of chambers corresponding to the number of 

 carpels ; they may be parietal or on the walls, the ovary unilocular ; or they may 

 be free-central with unilocular ovary. In the case of parietal placentae, they often 

 project so far into the ovary as at first sight to chamber it. 



The concrescence of the carpels may also include the styles or the styles and 

 stigmas. 



The internal structure of the ovule need not be considered here, but a few 

 external points are important. It is borne upon the placenta by a stalk or funicle. 

 When fertilised by the entrance of the tube that grows out from a pollen grain 

 resting on the stigma, it grows into a seed, covered by a seed-coat or testa. 



The ripe seed contains an embryo which under proper conditions may grow 

 into a new plant, and there may be, between the embryo and the seed -coat, some 

 endosperm or albumen, a whitisli oily or starchy tissue, being the food upon which 

 the young plant has to live till it has come above ground and got green leaves of its 



