| Abstract: | The family Cephalotaxaceae contains only one genus, Cephalotaxus, with 9 species and some varieties, mostly endemic to China.
The present paper deals with the comparative anatomy of secondary phloem of stems in 4
species and I cultivar, of this genus under light microscope and scanning electron microscope.
The main results are as follows:
(1) The structure of secondary phloem is rather uniform in the various species of this
genus. In cross section, sieve cells, phloem parenchyma cells form continuous tangential rows
of one cell in width respectively, which occur alternately. Sclerenchyma cells also form continuous tangential rows, each with a radial width of 1-4 cells. The interval between the rows
is rather wide.
(2) The type of phloem fiber and the quantity of sclereids can be served as the characters for identification of species and the evidence for the separation of two sections of Cephalotaxus, namely: Cephalotaxus and Pectinatae.
(3) The secondary phloem of this genus contains more or less crystalliferous parenchyma
cells, in the inner tangential walls of which calcium oxalate crystals are embedded. So far this
character has not been reported in the other families and the genera of conifers. Our conclusion, therefore, agrees with the opinion that Cephalotaxaceae is a natural taxon and includes
only one genus, Cephalotaxus. |
