258 FRUITS AND SEEDS. 



follicles and many capsules, e.g. those of Poppy and Cam- 

 panula (Harebell, Canterbury-bell), which open by pores ; 

 those of Campions, Stitchworts, Primroses, etc., which open 

 by teeth at the top ; besides in capsules opening by slits or 

 a lid ; also in the fruiting heads of some Composites which 

 have no pappus on their akenes, e.g. Sunflower. 



As an aid to wind-dispersal, seeds are frequently flattened 

 (Wallflower, etc.), as also are the fruit- segments of Um- 

 bellifers and the akenes of Buttercups and Composites. 



Very commonly, however, special structures are present 

 which enable seeds, or more frequently akenes, to be more 

 readily carried by the wind. The plumed seeds of the 

 Willow, Poplar, Willow-herb (Epilobium) , Bog Asphodel, 

 and Cotton-plant have hairy outgrowths. Winged seeds 

 occur in Pines, Yellow Rattle, Deutzia, and Bignonia 

 (" Trumpet-flower "). 



The winged akenes (samaras) of the Ash, Elm, and 

 Birch afford good examples of winged fruits in which the 

 wing is an outgrowth of the pericarp. In the Maple and 

 Sycamore each fruit splits into two or three winged 

 samaras. The Hornbeam has persistent bracts which 

 form a wing on the fruit; a similar bract- wing occurs in 

 the Hop. In the Lime-tree (Tilia) the stalk bearing the 

 cluster of nuts hangs down, and the large bract attached to 

 it acts as a kite or aeroplane. Bracts also act as wings to 

 the fruits of Bougainvillea and Mirabilis (Marvel of Peru) 

 two tropical but commonly cultivated plants. In Docks 

 the fruit is covered by the " calyx," which bears three wings. 

 In some cases the wing is funnel-shaped, or parachute-like, 

 as in Thrift (persistent papery calyx) and Teasel (persistent 

 bracts around the flower). 



A few examples of plumed fruits (i.e. fruits bearing hairs 

 or hairy appendages) may be given. In Clematis, Pasque- 

 flower, and Dryas each akene has a persistent hairy style; 

 in Cotton- sedge the fruit bears numerous long silky hairs, 

 produced by the perianth; in Bulrushes hairs are pro- 

 duced by the stalk on which each fruit is carried. The most 

 highly developed plumed fruits occur in Valerians and 

 many Composites; in these plants the calyx grows after 

 fertilisation, and forms a ring of hairs (the pappus) on the 

 top of the fruit. Good examples are seen in the Dandelion 



