HYBRIDS 179 



Azalea Mortieriana Spae in Ann. Soc. Agric. Bot. Gand, II. 325, t. 81 (1846), 



in part (twelve named varieties are figured). 

 "Azaleae Mortierianae " Morren in Ann. Soc. Agric. Bot. Gand, 9, t. 106 



(1847), in part. 

 Azalea pontica et var. Witte, Flora, 290, t. 73 (1868). 

 Azaleae Gandavenses K. Koch, Dendr. II. 185 (1872), as synons. 

 Azalea Gandavensis Hort. apud K. Koch, Dendr. II. 2, 367 (1873), in the 



index. — Rehder in Bailey, Cycl. Am. Hort. I. 121 (1900), in part. 



This collective group is intended to include all the hybrids between the different 

 species of American Azaleas (exclusive of R. occidentale) and B. luteum which can- 

 not be traced to any of the binary hybrids but are apparently of more mixed and 

 uncertain parentage. It comprises the garden forms known as Ghent Azaleas or 

 Azalea pontica varieties, also sometimes called Azalea Mortieriana, though Rhodo- 

 dendron Mortieri as first figured and described by Sweet is apparently a binary 

 hybrid between R. calendulaceum and R. nudiflorum. As it is desirable for prac- 

 tical reasons to have a definite name for this group of hybrids, I have adopted the 

 name gandavense, which has been used in some nursery catalogues in the combina- 

 tion "Azaleae gandavenses" for this group of hybrids. It is one of those cultigen 

 groups which as L. H. Bailey points out (in Science, XLVII. 306 [1918]) need 

 names in the taxonomic treatment of cultivated plants, though such groups can- 

 not be pinned down to a type and are more or less heterogenous and therefore not 

 exactly in accordance with present taxonomic usage. 



The following forms seem also to belong here: 



"Azaleas de Jardins " Lemaire in III. Hort. II. pi. 75 (1855). 



Sixteen different named varieties are figured, a flower of each; most of them are 

 similar to the forms of R. Morteri, some suggest the influence of A. speciosum and 

 some of R. luteum. 



"Azaleas rustiques de Gand " Van Houtte in Rev. Hort. Beige, III. 3 tab. 

 (1877). 



Two named varieties of the R. Mortieri type. 



"Hardy Azaleas " Osborn in Gard. XV 318 t. 176 (1879). 



Four varieties, probably all representing hybrids of R. Morteri. 



Rhododendron gandavense var. plenum Rehder, nom. nov. 



Under this name all the double-flowered forms of R. gandavense may be classed. 

 I refer here the following forms, of which the first may serve as a type of this group. 



Azalea Van Houttei flore pleno Van Houtte in Fl. des Serres, XIII. t. 1298 

 (1858). 



Raised from seed of a form of R. Mortieri. The flowers are semidouble with 

 5 to 10 stamens, and of pink color with the 3 or 4 upper lobes orange. 



"Azaleas rustiques de Gand " Van Houtte in Fl. des Serres, XIX. t. 2019- 

 2024 (1873), excl. t. 2019, 2020. 



The plants were bought by Van Houtte from the widow and sons of Louis 

 Hellebuyck, a contemporary of Mortier. Six forms are figured; four of them are 

 double-flowered, two of them (t. 2019 and 2020) are single. 



"Hardy double Azaleas " Moore in Flor. & Pomol. 1880, 89. t. 516. 



