ALDER : PLANE 97 



Alnus glutinosa, L. Alder (Fig. 95). The beginner 

 will have to be on his guard respecting the cone-like 

 infructescences of Alnus. 



The racemose branching of the pedunculate "cones," 

 the complex nature of their scales, and the one-seeded, 

 indehiscent achenes bearing scars or remains of stigmas, 

 sufficiently distinguish them from true cones. Their 

 being erect, woody, and persistent, and bearing achenes, 

 at once distinguish them from Willows and Poplars ; 

 and the mere border to the achenes, in place of a distinct 

 membranous winged margin, as well as their being in 

 pairs, sufficiently differentiates them from the Birches, 

 especially if the characters of the "cones" are borne in 

 mind. 



** Fruits not shed from between the scales 

 of an elongated catkin. 



t Fruits aggregated in globose heads. >r 



Fruit-heads (infructescences), sessile on pen- 

 dent long stalks, deciduous and shedding 

 the achenes (caryopsis) after falling ; each 

 achene wedge-shaped, with a tuft of hairs 

 surrounding the pointed base. 



Platanus orientalis, L. (and P. acerifolia). The 

 globose " button " is composed of the whole pistillate 

 inflorescence, and is therefore an infructescence (multiple 

 fruit) when it falls. There is no similar tree likely to 

 be encountered, as Platanus occidentalis is exceedingly 

 rare in Europe. 



The comose seeds of Tamarix, Poplars and Willows 

 are set free from the true fruits while these are still 

 attached to the spikes or catkins as they hang from the 

 tree ; the superficially similar achenes of the Plane 

 (Platanus) with their basal tuft of hairs may not fall 

 w. iv. 7 



