Die Nektarien der Apiaceae

Abstract

Summary This paper deals with the morphology and anatomy of the nectaries of the Apiaceae , particularly of the Saniculoideae and the Hydrocotyloideae which are thought to be not so highly evolved. The analysed parameters show a surprisingly great variation. Typically the nectary is developed on the foot of the stylodia. There are three phylogenetical tendencies (Fig. 9): 1. A centrifugal shift over the roof of the loculaments to adaxial parts of the peripherical phylloms and/or to the adaxial parts of a gamophyllous pedestal (a); 2. an acrocentrical shift to the tips of the stylodia (b); 3. an also acrocentrical shift in the genus Actinotus but with a completely different gynoeceal structure (c). — The term stylopodium cannot therefore be used for all nectaries of the Apiaceae. — The nectariferous tissue is located both on the phyllomes and on the axes of the epigynous flower. — The nectarothecas have when present a small capacity. There are three types: 1. simple depressions in the nectary itself; 2. cavities resulting from the growth of stylodia, ovary-roof and the nectary halves; 3. Cavities formed by growth of a peripherical torus and the ovary-roof; there are several variations of the latter (e.g. pseudoseptale nectary) depending on the intercalary meristem activity. The vertical anatomical structure is uniform: epiderm with transformed stomata, nectary parenchym, normal parenchym, conductive tissue. On the other hand there is a great variety of the epiderm cells: block-shaped, papillary, hairy. In a few cases the nectary can be multifunctional: 1. attraction of the pollinators by intensive colouring; 2. postfloral function as an elaiosom; 3. it can perhaps also have a protective function and 4. may serve as a second stigmatoid surface. The phylogeny of the nectary is discussed.