Broom stem, LM 照片檔

Broom stem. Light micrograph (LM) of a transverse section through the stem of a common broom (Salicornia europaea) plant. Broom is a drought plant (xerophyte) with ribbed stems and branches to increase the area for photosynthesis. The ribs (spikes) contain spongy mesophyll, similar to a leaf, in the centre and ends of which are supporting bundles of fibres (sclerenchyma) The stem has undergone secondary thickening to produce a ring of xylem Above the xylem is the cambium and above this is the phloem In the centre of the stem is the pith made up of parenchyma cells. Magnification: x60 when printed 10 centimetres wide.