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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Some Biological Notes. 



It adds considerably to the interest of cultivating any particular group 

 of plants to take note of any morphological or physiological variations or 

 peculiarities that may be displayed therein. 



Irises furnish some points that may be worthy of note. 

 The Variation in Colour of the Pollen. — Taking the bulbous species 

 first, Iris Histrio and I. histrioides, Iris Danfordice, and I. xiphioides 

 have white pollen ; Iris reticulata, I. Krelagei, I. Boissieri (fig. 122), 

 and I. filifolia have' yellow pollen, while that of /. Bakeriana and I. 

 Xiphiumis golden. In the 'Juno' group we find that Iris caucasica 

 and Iris sindjarensis have white pollen. In the 1 Regelia ' group that of 

 Iris Korolkoivi (fig. 131) is green, and in I. Leichtlini it is white. In 

 the 1 Oncocyclus ' group Iris susiana (fig. 133) has white pollen. It is 

 the same in Iris stylosa (fig. 134), but it is yellow in Iris tuberosa (fig. 

 135). In Iris arenaria (fig. 136) it is slaty-blue, and in Iris verna 

 white. In the ' Pumila ' group and in Iris Statellce (fig. 137) it is white, 

 except in Iris nudicaulis, when it is green, while it is blue in Iris 

 lenacensis. In the various species forming the ' Germanica ' group it is 

 white, except that it is pale yellow in Iris florentina and cream-coloured 

 in Iris variegata. The tall Flags, as Iris ochroleuca and Iris Pseudacorus, 

 have yellow pollen, but in the smaller I. graminea it is orange. In 

 the water-loving Flags, as Iris virginica, it is white, and also in the 

 ' Sibirica ' group, but with a greenish tinge in I. orientalis, and in 

 I. longipetala superba it is yellow. The colour of the pollen therefore 

 appears to be somewhat arbitrary, and valueless as a morphological 

 character for separating the various groups. White and yellow are, as 

 might be expected, the commonest colours. 



Fragrance. — Another point for observation is the presence or absence 

 of fragrance in the flowers, and the character and degree of the same. 

 There are not many Irises that smell sweetly, and they may be most easily 

 grouped under the heading of the scents, for there is little variety. Iris 

 pallida and dalmatica are very strongly scented with a rich nutty fragrance 

 which may be taken as the typical Iris perfume. The only other scented 

 species in the « Germanica ' group is Iris sambucina, with its distinct 

 Elder-flower odour. Lily of the Valley is the scent recalled by Iris italica 

 and hybrids of Iris pumila and Iris olbiensis (fig. 137) ; this scent is also 

 slightly present in I. sibirica, and so strongly in Iris Leichtlini (fig. 132) 

 that qne blossom will scent a room. Violet scent belongs to Iris reticu- 

 lata and I. Bakeriana, and is just perceptible in Iris Krelagei ; it is also 

 present in Iris verna. Iris Vartani is vanilla-scented. 



Attar of rose is strongly developed in Iris tuberosa and I. stylosa, and 

 is also present in a lesser degree in Iris Histrio and Iris Statellce. A long 

 list of scentless species might be added, including some of the Bulbous 

 group, as Iris histrioides, 1. Boissieri, &c., the 'Juno' and * Oncocyclus ' 

 groups, the Flags, and most of the 1 Apogon ' group. 



In some of the Irises the scent globules appear to be situated in the 

 standards, giving them a glistening and pellucid appearance ; in others the 

 scented nectar collects around the base of the stigmas. 



