ELEMENTARY BOTANY. XU1 



in shape, colour, and arrangement round the axis, and often more or less combined with 

 each other. The details of this theory constitute the comparatively modern branch of 

 botany called Vegetable Metamorphosis or Homology, sometimes improperly termed 

 Morphology (8). 



89. To understand the arrangement of the floral parts, let us take a complete flower, 

 m which moreover all the parts are free from each other, definite in number, i.e. always 

 the same in the same species, and symmetrical or isomerous, i.e. when each whorl con- 

 sists of the same number of parts. 



90. Such a complete symmetrical flower consists usually of either four or five 

 whorls of altered leaves (88), placed immediately one within the other. 



The Calyx forms the outer whorl. Its parts are called sepals. 



The Corolla forms the next whorl. Its parts, called petals, usually alternate with 

 the sepals ; that is to say, the centre of each petal is immediately over or within the 

 interval between two sepals. 



The Stamens form one or two whorls within the petals. If two, those of the outer 

 whorl (the outer stamens) alternate with the petals, and are consequently opposite to, 

 or over the centre of the sepals ; those of the inner whorl (the inner stamens) alternate 

 with the outer ones, and are therefore opposite to the petals. If there is only one 

 whorl of stamens, they most frequently alternate with the petals; but sometimes they 

 a reoppositethe petals and alternate with the sepals. 



The Pistil forms the inner whorl ; its carpels usually alternate with the inner row 

 oi stamens. 



91. In an axillary or lateral flower the upper parts of each whorl (sepals, petals, 

 stamens, or carpels)' are those which are next to the main axis of the stems or branch, 

 the lower parts those which are furthest from it ; the intermediate ones are said to be 

 lateral. The words anterior (front) and posterior (back) are often used for lower and 

 upper respectively, but their moaning is sometimes reversed if the writer supposes 



oo el !n in the centre of the flower instead of outside of it. 



92. The number of parts in each whorl of a flower is expressed adjectively by the 

 loliowing numerals derived from the Greek :— 



mono-, di-, tri-, tetra-, ponta-, hexa-, hepta-, octo-, ennea-, deca-, etc., poly- 

 '-. 2-, 8-, 4-, B-, 6-, f., 8-, 9-, 10-, vtany- 



Pr QQ X6 ^ t0 a termin ation indicating the whorl referred to. 

 y-J. Thus, a Flower is 

 disepalous, trisepalous, tetrasepalous, polysepalous, etc., according as there are 2, 

 °> % or many (or an indefinite number of) sepals, 

 petal petalous > tripetalous, polypetalous, etc., according as there are 2, 3, or many 



sta diandrous > triandrous, polyandrous, etc., according as there are 2, 3, or many 



digynous, trigynous, polygynous, etc., according as there 2, 3, or many carpels. 

 And generally (if symmetrical), dimerous, trimerous, polymerous, etc., accord^ 

 9 ^ ev J are 2 > 3, or many (or an indefinite number of) parts to each whorl, 

 the \ i Wer8 are asymmetrical or anisomerous, strictly speaking, when any one of 

 e whorls lias a different number of narts from anv other : but when the carpels alono 



the V. l " JC unsymmeiricai or anisomerous, Binuuj opuomug, ,...^.» ~~j — 



are ZT has a diir ° re nt number of parts from any other ; but when the carpels alono 

 if th i d ln number > the flower is still frequently called symmetrical or isomerous, 



ML T7i ' corolla > and staminal whorls have all the same number of parts, 

 size H- • ers are irre 9*lar when the parts of any one of the whorls are unequal in 

 It m l 88umlar in shape, or do not spread regularly round the axis at equal distances, 

 tions i eVer more es P e <-' ial ty irregularity of the corolla that is referred to in desenp- 

 tlie a 8hght inequality in size or direction in the other whorls does not prevent 

 gular ° r bemg cIaS8ed M regular, if the corolla or perianth is conspicuous and ro- 



§ 9. The Calyx and Corolla, or Perianth. 



mim,'t The Caly * (9°) w "dually green, and smaller than the corolla ; sometimes very 

 Ute > rudimentary, or wanting, sometimes very indistinctly whorled, or not whorled 



