The plant of
Dictyosiphon foeniculaceus has unilocular sporangia and liberates zoospores, from which the microscopic gametophytes develop. The isogamous gametes are made in the small stick-like plurilocular gametangium on the microphyte. The zygote germinates and makes up a creeping protonema-like germling, on which a monosiphonous protuberance sprouts. The monosiphonous thread grows and is enclosed by the cortical cells those have divided from the central thread. Thus a polystichous plant-body is made. From the view point of the polystichous construction, Profs. Kylin and Papanfuss said recently that Dictyosiphonales should be included in or lumped with Punctariales. But the writer is of opinion that so-called polystichous construction must be divided into two originally different types: a) a central thread does not appear, and the body is thallous from the start (such as Punctariales), and b) in the first stage, a monosiphonous central thread or such central body appear and then the cortical cells are formed from these (such as Dictyosiphonales). So Profs. Kylin's and Papenfuss opinions seem not to be reasonable.
In the other hand, the construction of
Chordarialeous plants are classified into three typas: a) compased of many furcately or sympodially ramified threads (such as
Petrospongium, Tinocladia,
Ishige & Myriocladia), b) composed of a central monosiphonous threads and the cortical threads around it (such as
Chordaria?, Acrothrix), and c) composed of a conical central body (polysticous?) and the cortical threads around it (
Sphaerotrichia). From this view-point, it is suggested that Dictyosiphonales may be included in or, at least, mostly related with Chordariales.
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