Anatomical studies on seed coats with characteristic patterns in subfamilies Caesalpinioideae and Mimosoideae (Leguminosae) in relation to their function and phylogeny

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Pleurogram-areole and pitted patterns on seed surface were anatomically investigated and compared in subfamilies Caesalpinioideae and Mimosoideae (Leguminosae) in relation to their function and phylogeny.1.From anatomical investigations on seeds from 19 genera 67 species, the following results were obtained :(1)Two types were recognized in seeds with pleurogram-areole pattern : one has the pleurogram as a line without crack which is the border of two different tissue structures in the seed coat ("non-crack pleurogram") and the other has the pleurogram as a crack ("crack pleurogram"). The both types are found in Caesalpinioideae, while only the latter found in Mimosoideae. (2)No histological difference was found around the crack pleurogram, while obvious histological differences were found in seeds with non-crack pleurogram or pitted pattern.(3)The crack pleurogram was found only in genera of Dimorphandra group in Caesalpinioideae, which is located on the closest position to the Mimosoideae on the basis of recent molecular data. The crack pleurogram also supports the phylognetic position of the group. (4)Two types were recognized in fracture lines, which are borne on the whole seed coat, by the depth. Deep fracture lines were found within the areole or the pit, while the shallow one outside the area. (5)The seed coats of three allied genera Cassia, Senna and Chamaecrista in subfamily Caesalpinioideae, although they have different seed surface patterns, were structurally connected to each other by similarity in anatomical features.2.From water infiltration test after immersing seeds in water using Albizia, Senna and Chamaecrista, the following functional features were suggested :(1)The crack pleurogram has no relation to water infiltration. (2)The non-crack pleurogram and the pit have no direct relation to water filtration but they appear to contribute to soften seed coat.