(1) Studies have been made particularly on the so-called petiolar base of the Ophioglossaceae from the view point of vascular course, dichotomy and phyllotaxis, mainly based on the observation of
Botrychium japonicum.
(2) Vascular courses within this part can be divided into 3 different types, according to its structure, viz. Single-arc, Double-arc and Ring types. Though Chrysler observed the presence of these 3 types in the different species of
Botrychium, I found the presence of these in different individuals of this single species.
(3) The manner of departure of vascular traces of the petiolar base from the central cylinder of the rhizome is essentially different from the dichotomy which can be seen at the upper part of the petiole: the former, therefore, may be named “Sympodial dichotomy, ” while the latter, “True dichotomy.”.
(4) Sympodial dichotomy of the so-called petiolar base has been greatly influenced by the monopodial branching of the rhizome.
(5) According to the former authors, this part has been regarded as the base of petiole or a part of a leaf, but it seems unsatisfactory for me. This part may be, therefore, considered as an intermediate organ of the rhizome and the petiole, carrying both sterile and fertile fronds, and may be called as “Phyllomophore.”
(6) The above mentioned facts are to be seen also in some species of
Ophioglossum.
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