AN ENCYCLOPAEDIA OF HORTICULTURE. 



181 



Pollination continued. 



flowers are protected under net or glass, they wither 

 and fall without the anthers getting free or the stigma 

 being Pollinated, and the flowers remain barren. But, 

 in the natural condition, the flowers are freely visited 

 by various Bees, and other insects, which usually alight 

 on the style, and, in sucking the nectar, come into con- 

 tact with the filaments, and set free the anthers one by 

 one. The filaments straighten themselves, and the pollen 



FIG. 220. DETAILS OP KALMIA LATIFOLIA. 



A, Expanded Flower ap, Anther Pocket B, Section of Expanded 

 Flower op, ap, Anther Pockets ; *, Stigma ; a, Free Anther ; 

 pg, Pollen Grains in Shower ; co, Calyx. C, Section of Flower 

 Bud ap, Anther Pocket D, Stamen, more enlarged a, 

 Anther ; po, Tores ; pg, Pollen Grains ; /, Filament. 



is thrown out of the anther, from two small holes at the 

 tip (see Fig. 220, D), against the insect's body, to be thus 

 transported to the stigma of another flower. Such 

 flowers as characterise the Labiates, the Orchidece, and 

 the papilionaceous Leguminosce, in possessing bilateral 

 symmetry, are among the peculiarly entomophilous 

 types, especially when the nectar is so placed as to be 

 accessible only to insects possessed of a long proboscis, 



FIG. 22L POLLINATION OP ORCHID. 



A, Flower of Orckit Morio (Sepals, two Petals, and side of Spur 

 removed), with Hive Bee sucking Nectar a, Anther; jx>, 

 Pollinium ; r, Rostellum ; ft, Stigma (side view) ; I, Labellnm ; 

 or, Orary ; n, Nectary ; br, Bract B, Head of Bee, carrying 

 (po) Pollinium n, Antenna?. 



e.g., Bees (see Fig. 221). In addition to this, in some 

 e.g., in Antirrhinum (see Fig. 222), the corolla is closed by 

 the lower lip, which is pressed against the upper one, 

 and excludes all but insects heavy enough to depress it, 

 e.g., Humble Bees. In the strictly entomophilous flowers, 

 very striking adaptations to favour the visits of insects 

 of certain groups, or even of certain species, and to 

 exclude other insects, are often met with. But the field 

 is so wide, that to give examples would far exceed the 



Pollination continued. 



space here available. Eeaders are therefore referred to 

 the works noted above, and their attention is called 

 to a subject of the utmost interest in itself, and of 

 great practical value in its relations to hybridising 



FIG. 222. FLOWER OP AXTIRRHI.VCM OROXTIUIL 



plants, and to the development of new races of value 

 for their beauty, or for other properties suited to com- 

 mend them to gardeners and to amateurs. 



FOLLINIA. Pollen-masses. 



POLY. In Greek compounds, this signifies numerous; 

 e.g., Polycotyledonous, having several cotyledons. 



POLYACTIDIUM. Included under Erigeron. 



POLYADELPHIA. A Linnsean artificial order, 

 characterised by having stamens in several phalanges. 



POLYAIiTHIA (from polys, much, and altheci*, 

 healthy; alluding to supposed . properties of the plant). 

 OBD. Anonaceae. A genus comprising about thirty species 

 (including twenty-five which are sometimes classed with 

 Guatteria,) of stove or greenhouse trees or shrubs, natives 

 of tropical Asia, one being Australian. Flowers solitary 

 or fasciculate, axillary or opposite the leaves ; sepals 

 three, valvate or rarely loosely imbricate ; petals six, 

 bi-seriately valvate, flat, almost equal, ovate or narrow. 

 Leaves oblique, penniveined. The two species described 

 below are the only ones worth mention. They are stove 

 trees. For culture, see Gnatteria. 



P. cerasoides (Cherry-like), it, peduncles axillary, solitary; 



petals nearly equal. 1. lanceolate, acute, pubescent beneath. 



A. 60ft East Indies, 1820. 

 P. snberosa (corky-barked). /., three outer petals greenish, the 



three inner ones whitish ; peduncles nearly opposite the leaves, 



one-flowered. I. oblong, acute, smooth. A. 30ft India, 1820. 



POLY AND HI A. A Linnsean class, having flowers 

 with an indefinite number of stamens. 



POLYANTHUS. A synonym of Polyxena (which 

 see). 



POLYANTHUS. A garden race of Primula, pro- 

 bably derived from a cross between the Primrose and 

 Cowslip. The Polyanthus has been in cultivation for 

 many years, and has proved itself one of the most 

 popular of florists' flowers. The attention, however, now 

 bestowed on it is much less than at an earlier period 

 of its history, and the varieties raised are far less 

 numerous. Good varieties, that were once procurable, 

 are now lost to cultivation, and those of the present 

 day are not generally considered of equal merit at 

 least, for exhibition purposes. As a hardy garden 

 plant, the Polyanthus is likely to remain a favourite, 

 and deservedly so, for planting on mockeries, in mixed 

 borders, and in spring flower-beds. The vigorous-growing 

 varieties, which may be readily raised from seed, are 

 admirably adapted for naturalising in pleasure-grounds 

 along the sides of walks, &c. Florists' rules regarding 

 the flowers of a Polyanthus, and the recognised qualities 

 exhibited in them, are very rigid ; it is, however, un- 

 necessary to follow them too closely, unless the flowers 

 are required for exhibition. For the last-named purpose, 

 the section known as Gold-laced is most favoured; the 



