Abstract
1) Various forms of Saccharum spontaneum collected from different parts of Formosa can be, in general, divided into two categories, small and large. The smaller plant, below 2m in height with a glabrous ligule, is S. spontaneum subsp. indicum var. genuinum, the chromosome numbers being n=56, 2n=112. The larger one, taller than 2m in height with a ciliate ligule, is S. spontaneum subsp. indicum var. Roxburghii, the chromosome numbers of which are n=48, 2n=96. The relation between the plant height and the chromosome number shows a sheer contrast compared to the cases in S. spontaneum reported by some investigators to date. In Formosa, both kinds of spontaneum are found on the plains and mountains below the elevation 500m, especially on the banks of rivers or seashores.
2) Any number of chromosomes other than above mentioned two was found in naturally grown spontaneum of Formosa, though a considerable difference in morphological characteristics was seen within each variety.
3) The distribution map of S. spontaneum in South-eastern Asia and its vicinity was presented, and the area was divided as follows according to the number of chromosomes of the plants growing:
I. Malay Archipelago and South Seas Section........ Philippines, Micronesia, New Guinea involved.
II. India-Burma Section........ Turkmenistan involved.
III. Japan Islands Section....... Formosa, Okinawa involved.
4) Speciality in the mode of distribution and chromosome numbers of S. spontaneum in India, as well as the existence of abundant kinds of cultivated sugar cane there, suggests us that at least one of the keys to unlock the question of unknown ancestral sugar cane forms seems to be concealed in the northern part of India.
5) S. spontaneum subsp. indicum var. genuinum of Formosa and Glagah of Java, appear to be phylogenetically different, though the number of chromosomes is the same (2n=112). This conclusion may be drawn from the facts that: (1) they are different in external aspects, (2) two islands under consideration seem to have no geographical connection concerning the distribution of S. spontaneum, other kinds of spontaneum with different numbers of chromosomes being found in the districts between Formosa and Java, and (3) S. spontaneum in Hainan and Philippine islands, lying nearest to Formosa, are considered to be different from genuinum of Formosa, making the distribution of genuinum in Formosa isolated from near lying islands.
6) Narenga porphyrocoma in Formosa is n=15, which is the same as Javanese and Indian materials. This plant shows sometimes high degree of polyvalent conjugation in meiosis of PMC-s.
