INTRODUCTION. Xlll 



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

 more flowers. 



a Head, or capitate, when several sessile or nearly sessile flowers are collected 

 into a compact head-like cluster. The short, flat, convex or conical axis on which the 

 flowers are seated, is called the receptacle, a term also used for the torus of a single 

 flower (135). The very compact flower-heads of Composite are often termed compound 

 flowers. 



an Umbel, or umbellate, when several branches or pedicels appear to start from 

 the same point and are nearly of the same length. It differs from the head, like the 

 raceme from the spike, in that the flowers are not sessile. An umbel is said to be 

 simple, when each of its branches or rays bears a single flower ; compound, when each 

 ray bears a partialtimbel or umbellule. 



a Corymb, or corymbose, when the branches and pedicels, although starting from 

 different points, all attain the same level, the lower ones being much longer than the 

 upper. It is a flat-topped or fastigiate panicle. 



a Cyme, or cymose, when branched and centrifugal. It is a centrifugal panicle, 

 and is often corymbose. The central flower opens first. The lateral branches succes- 

 sively developed are usually forked or opposite (dichotomous or trichotomous), but 

 sometimes after the first forking the branches are no longer divided, but produce a suc- 

 cession of pedicels on their upper side forming apparently unilateral centripetal racemes ; 

 whereas if attentively examined, it will be found that each pedicel is at first terminal, 

 but becomes lateral by the development of one outer branch only, immediately under the 

 pedicel. Such branches, when in bud, are generally rolled back at the top, like the tail 

 of a scorpion, and are thence called scorpioid. 



a Thyrsus, or thyrsoid, when cymes, usually opposite, are arranged in a narrow 

 pyramidal panicle. 



75. There are numerous cases where inflorescences are intermediate between some 

 two of the above, and are called by different botanists by one or the other name, ac- 

 cording as they are guided by apparent or by theoretical similarity. A spike-like panicle, 

 where the axis is divided into very short branches forming a cylindrical compact inflo- 

 rescence, is called sometimes a spike, sometimes a panicle. If the flowers are in dis- 

 tinct clusters along a simple axis, the inflorescence is described as an interrupted spike 

 or raceme, according as the flowers are nearly sessile or distinctly pedicellate ; although 

 when closely examined the flowers will be found to be inserted not on the main axis, 

 but on a very short branch, thus, strictly speaking, constituting a panicle. 



76. The catkins (amenta) of Amentaceee, the spadices of several Monocotyledons, 

 the ears and spiheleis of Grasses are forms of the spike. 



77. Bracts are generally placed singly under each branch of the inflorescence, and 

 under each pedicel ; bracteoles are usually two, one on each side, on the pedicel or close 

 under the flower, or even upon the calyx itself ; but bracts are also frequently scattered 

 along the branches without axillary pedicels ; and when the differences between the bracts 

 and bracteoles are trifling or immaterial, they are usually all called bracts. 



78. When these bracts appear to proceed from the same point, they will, on exami- 

 nation, be found to be really either one bract and two stipules, or one bract with two 

 bracteoles in its axil. When two bracts appear to proceed from the same point, they 

 will usually be found to be the stipules of an undeveloped bract, unless the branches 

 of the inflorescence are opposite, when the bracts will of course be opposite also. 



79. When several bracts are collected in a whorl, or are so close together as to appear 

 whorled, or are closely imbricated round the base of a head or umbel, they are collec- 

 tively called an Involucre. The bracts composing an involucre are described under the 

 names of leaves, leaflets, bracts, or scales, according to their appearance. Phyllaries is 

 a useless term, lately introduced for the bracts or scales of the involucre of Composites. 

 An Involucel is the involucre of a partial umbel. 



80. When several very small bracts are placed round the base of a calyx or of an 

 involucre, they have been termed a calycule, and the calyx or involucre said to be cal- 

 culate, but these terms are now falling into disuse, as conveying a false impression. 



81. A Spatha is a bract or floral leaf enclosing the inflorescence of some Monocoty- 

 ledons. 



