Juncaceae
Phylogeny Group
Juncus anatomy
1)
Case study of Juncus
uruguensis
Griseb. - a member of the section Juncotypus
(Juncaceae, Juncus
subg. Agathryon
Raf.)
Anatomy and morphology of Juncus uruguensis Griseb. were studied in order to determine the sectional position of the species. Leaf anatomy (Fig. 1), a decisive criterion for sectional classification in the subg. Agathryon, shows that the species should be placed in the sect. Juncotypus, not in the sect. Steirochloa.
Juncus uruguensis
is characterized by the following features of leaf anatomy:
Leaf T.S. is not round (it is usually ± elliptic,
see also Fig. 1) but is
polysymmetric, with distinct grooves and ridges; there is no
possibility to
distinguish adaxial side of leaf. Cellulae bullatae are absent,
vascular bundles
are arranged in one subepidermal circle, and are connected to epidermis
by broad
strands of sclerenchyma. Separate sclerenchyma strands are lacking.
Bundle
sheaths are parenchymatous. Pith is parenchymatous, later coalescent.
Epidermis
is formed by small cells and covers the entire blade surface. Epidermal
cells
are slightly enlarged on the ridges.
When the leaf T.S. characters of J. uruguensis are compared with those given in the, J. uruguensis is to be classified as a member of the sect. Juncotypus. The other characters either point to the sect. Juncotypus or are intermediate between the two sections.
Fig.
1
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