10 INTEODTTCTION. 



before it is developed. They are however exceedingly variable in size and 

 appearance, sometimes exactly like the true leaves, or looking like leaflets of 

 a compound leaf, sometimes apparently the only leaves of the plant ; 

 generally small and narrovr, sometimes reduced to minute scales, spots, or 

 scars, sometmies united into one opposite the leaf, or quite detached from 

 the leaf, and forming a ring or sheath round the stem in the axU of the leaf 

 In a great number of plants they are entirely vranting. 



§ 7. Inflorescence and its Bracts. 



The Inflorescence of a plant is the arrangement of the flowering 

 branches, and of tlie flowers upon them. An Inflorescence is a flowering 

 branch or the flowering summit of a plant above the last stem-leaves, with its 

 branches, bracts, and flowers. 



A single flower or an inflorescence is terminal when at the summit of a 

 stem or leafy branch, axillary when in the axil of a stem-leaf. The in- 

 florescence of a plant is said to be terminal or determinate when the main 

 stem and principal branches end in a flower or inflorescence, axillary, or in- 

 determinate, when all the flowers or inflorescences are axillary. 



A 'peduncle is the stalk of a solitary flower, or of an inflorescence, that is to 

 say, the portion of the flowering branch from the last stem-leaf to the flower, 

 or to the first ramification of the inflorescence, or even up to its last ramifi- 

 cations. 



A scape or radical peduncle is a peduncle that proceeds from the stock, 

 or from so near the base of the stem as to appear radical, provided always 

 that it bears no leaves at aU, or that the leaves are all reduced to small scales 

 or bracts. 



A pedicel is the last branch of an inflorescence, supporting a single 

 flower. 



Inflorescences, like stems, may have their branches opposite, alternate, or 

 scattered ; dichotomous, trichotomous, or umbellate. 



Inflorescence is 



centrifugal, when the terminal flower opens first, and those on the 

 lateral branches are successively developed. 



centripetal, when the lowest flowers open first and the main stem con- 

 tinues to elongate, developing fresh flowers. 



Determinate inflorescence is usually centrifugal. Indeterminate inflo- 

 rescence is always centripetal. 



Both inflorescences may be combined in one plant, for it often happens 

 that the main branches of an inflorescence are centripetal, whilst the flowers 

 in the lateral branches are centrifugal; or vice versa. 



An Inflorescence is 



a Spike, or spicate, when the flowers are sessile along a single undivided 

 axis, called the rhachis. 



a Raceme, or racemose, when the flowers are borne on pedicels along a 

 single undivided axis, also often called the rhachis. 



a Panicle, or paniculate, when the axis is divided mto branches bearing 

 two or more flowers. 



a Head, or capitate, when the flowers are collected into a compact 

 globular or roundish cluster, compared to a man's he'ad. Strictly speaking 

 the head is either a globular spike or a globular panicle of which the branches 

 are excessively short. 



An Umbel, or umbellate, inflorescence, is a raceme in which all the pedicels 

 appear to start from the same point and are of nearly the same length, or 



