Beiträge zur Wuchsform und Biologie der Gefäßpflanzen des herzynischen Raumes.: 2: Smyrnium perfoliatum L. (Apiaceae)

Abstract

Smyrniurn perfoliatum, an alien established in few places in Germany, belongs to a genus of 5-7 species distributed in the Mediterranean-Submediterranean-Iranian region. S. perfoliaturn is a strictly Summergreen pluriennial monocarpic tuber geophyte with exclusively generative reproduction. The structure of the adult plant is strongly fixed. The orthotropous stem bears at its base 4 scale leaves, 2 stalked, biternate basalleaves, 2-3 biternate cauline leaves and 4-6 undivided amplexicaul yellow-green bracts. All these bracts but the lowermost one subtend paraclades. Each paraclade develops only the 2 bract-like prophylls, that may subtend paraclades of the 2nd order. The main stem and all paraclades are terminated by double umbels. Only the terminal main inflorescence and those of the paraclades of the Ist order produce fruits. The morphological character of the tuber emerges from its curious development. The vegetation point of the shoot becomes displaced into the primary root and is moved 6-8 cm into the soil with the growing root (the latter hitherto interpreted as cotyledonary sheath covered by root tissue). There a small tuber about 5 mm thick is developed from root and hypocotyle tissue in the spring of the germination year. During the 4-6 years of development to maturity, this tuber is thickened to about 2,5 cm. Every autumn it develops a few new roots, the proximal parts of which will become thickened and integrated into the tuber. Leaves of vegetative plants are alive from February to early June only, roots from October to June. Towards the end of June allleaves are withered. The generative plants have then only all the bracts and some roots alive, the biternate basal and cauline leaves being wilted long before. The dissernination time is towards the end of July. Distribution maps of all species of the genus Smyrniurn and illustrations of the developmental stages of S. perfoliaturn are provided.