Chromosome counts of 33 taxa of dwarf plants collected from Yakushima Island are reported. Chromosome counts for the following 23 taxa are published for the first time : Coptis ramosa（2n=18）, Sarothra laxa f. hananoegoensis（2n=16）, Astilbe glaberrima var. saxatilis（2n=14）, Parnassia palustris var. yakusimensis（2n=18）, Saxifraga fortunei var. minima（2n=22）, Viola boissieuana var. pseudoselkirki（2n=24）, V. verecunda var. yakusimana（2n=24）, Circaea alpina f. minima（2n=22）, Angelica longiradiata var. yakushimensis（2n=22）, Tripterospermum japonicum var. tenue（2n=46）, Galium pogonanthum var. yakumontanum（2n=22）, Mitchella undulata var. minor（2n=22）, Neanotis hirsuta var. yakusimensis（2n=24）, Clinopodium multicaule var. yakusimense （2n=20）, Scutellaria kuromidakensis（2n=26）, Melampyrum laxum var. yakusimense（2n=18）, Cirsium yakushimense（2n=68）, Heloniopsis breviscapa var. yakusimensis（2n=34）, Metanarthecium luteo-viride f. yakusimense（2n=52+1 B）, Smilax biflora var. biflora（2n=30）, Tofieldia yoshiiana（2n=30）, Luzula campestris var. yakusimensis（2n=12）, Pseudosasa owatarii（2n=48）. Chromosome counts for a further ten taxa agree with those already published : Ranunculus yakushimensis（2n=14）, Hypericum kiusianum var. yakusimense（2n=32）, Mitella doiana（2n=28）, Fragaria nipponica var. yakusimensis（2n=14）, Sanicula lamelligera（2n=16）, Lysimachiajaponica var. minutissima（2n=20）, Plantago asiatica var. yakusimensis（2n=24）, Cacalia yakusimensis（2n=60）, Solidago minutissima（2n=18）, Paris tetraphylla var. yakusimensis（2n=10）. No differences were found when comparing these chromosome numbers of dwarf plants with those of closely related non-dwarf taxa.
Yamamoto et al. (Tue,) studied this question.