INTRODUCTION 
the rest of the Buttercup Family they are imbricate , overlapping like 
tiles on a roof. Poppies have their petals crumpled. The Mallow Family 
have the sepals valvate and the petals convolute , that is, with one edge 
towards the centre of the flower, and the other rolled round the next petal. 
In Convolvulus the coherent petals are convolute but also twisted upwards, 
or contorted. 
The stamens vary greatly in number, from one in Lords- and-ladies, 
Spurge, and Spur-Valerian, two in Veronica and some Willows, three in Iris , 
^ four in Ladies-mantle, five in Umbel/ifera , or six in Lilies, 
up to an indefinite number in Buttercups ; and they may 
be arranged spirally or in one, two, or more whorls. Each stamen consists 
typically of a slender stalk or filament surmounted by the anther , an oblong 
or rounded body, generally two-lobed externally and, when ripe, two- 
chambered internally, which bursts and discharges the pollen. This usually 
occurs as a fine yellow dust, which, carried by wind or insects from one 
flower to another, is the active or male element in fertilisation or “ setting 
seed.” 
The stamens are commonly in one or two whorls and are accordingly 
either equal in number to, or double the number of, the petals ; but in 
some large groups of plants one or more stamens of such normal number 
are undeveloped or suppressed , or are imperfectly developed or aborted , 
producing no pollen. These last are termed staminodes. In other cases, 
such as the St. John’s-worts, the stamens branch, each bearing several 
anthers. These are termed polyadelphous (Greek 770X1)5, polus , many ; 
dSe\(£o 5 , adelphos , a brother). A tubular outgrowth from the receptacle 
may carry up all the stamens, as in the Mallows and in Gorse, when they 
are called monadelphous ; or they may be united in two sets, or diadelphous , 
as in most of the Pea and Bean Family, in which nine are so united 
and one — the upper one — is separate ; or they may be united by their 
anthers, as in the Family Composites, when they are termed syngenesious 
(Greek ow, sun, together ; yeVeo-is, genesis, beginning). In insertion they 
are, like the petals, hypogynous, perigynous, or epigynous ; but they may 
be united on a common tube with the petals, or epipetalous, as in the 
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