6 EXPLANATION OF THE TERMS USED 



{mono, one; cotyledon, seed leaf). Monocotyledons can be recognized in later life 

 by the leaves or leaflets being usually long and narrow, and nearly always without a 

 conspicuous network of veins. Very few are trees or shrubs. Not one of the 

 trees is a native of Europe, and only two shrubs : Butcher's Broom and Aspara- 

 gus. Not more than twenty genera of monocotyledons have been included in 

 this book, and most of these are unmistakable on account of their tropical or 

 grass-like appearance. Of the remainder Smilax and Lapageria are climbers, 

 while only Philesia and the Alexandrian Laurel, in addition to those already 

 mentioned, are shrubs. (All except the palms and banana are illustrated in 

 Figs. 38-40, which should be referred to in cases of doubt.) 



Nerves. The chief veins. 



Ob-. When the half towards the apex is broader than the half towards the base, 

 as in the pear or fig. Oblance-shaped (oblanc.) and obovate (obov.) mean, there- 

 fore, inversely lance-shaped and inversely ovate, i.e. the narrow end is towards 

 the point of attachment. (Fig. 74 l.) 



Oblong. Ovate or lance-shaped with sides nearly parallel, except at the base and 

 apex. Used also of fruits with approximately straight sides, i.e. neither egg- 

 shaped nor pear-shaped. (Figs. 40 d and 88 l.) 



Opposite. Arising in pairs from the same level, but on opposite sides. 



Ovary. The hollow chamber formed by the growth of the basal part of the carpel, 

 and completely enclosing one or more ovules. An ovary may be formed by one 

 carpel or by the union of several. It is said to be superior (Fig. 82 c) or inferior 

 (Fig. 94) when it is in a position above or below the insertion of the stamens and 

 other floral parts. Usually there is no difficulty in deciding this; but sometimes, 

 and particularly in the rose family, the ovaries may be borne in a hollow cup, 

 above or outside which the other floral parts are inserted. Where the cup is 

 definitely hollow, i.e. where there is a clear space between the ovary and the 

 sides of the cup, as in the plum and cherry (Figs. 90 and 91), the ovary must be 

 treated as superior. Where there is partial (Fig. 58 a) or complete (Fig. 58 d) 

 fusion, the ovary must be treated as inferior. 



Ovate (ov.). Shaped like an egg, i.e. with curved sides narrowing at the base and 

 apex. In this book any leaf narrowing to the stalk and less than three times 

 longer than broad, regardless of its actual outline. For example, 'Leaf ov., 

 3-5-lobed' means that the leaf is less than three times longer than broad, and 

 would be egg-shaped if the spaces between the lobes were filled up. The same 

 applies to leaves described as lance-shaped or linear. (Fig. 35.) 



Ovules. Tiny seed-like bodies, which may be seen when the ovary is dissected or 

 cut through (in conifers and shrubby horsetails the ovules are not enclosed in an 

 ovary; in the tree fern there is none). It is from the ovules, after they have been 

 fertilized by the pollen, that the seeds develop. (Fig. 82 c.) 



P. See Floral Formula and Perianth. 



Palmate. Arranged like the fingers of a hand, i.e. arising from approximately the 

 same point and spreading outwards. 



Palmately lobed. Where the midribs of the lobes are palmately arranged. 

 (Fig. 23.) This is an important point in the key. For example, the leaf of the 

 Wild Service Tree (Sorbiis Torminalis) appears at first sight to be palmately 

 lobed, and is so described in some books, but a reference to Fig. 36 k shows that 

 the midribs of the lobes are not palmately arranged ; the leaf is therefore pinnately 

 lobed. (Figs. 23-31.) 



