Abstract: Mytilaria laosensis seedlings of 50,60,70 and 80 cm height classes at 8 months age were selected for analyzing the morphological characteristics and their correlation between morphological indices aimed to provide references for seedling evaluation and grading.Ground diameter and ratio of height to diameter increased with height class significantly(P<0.01)while leaf number varied slightly with no significant differences between classes.Fresh plant weight and dry mass also increased with height class significantly(P<0.01),ranging from 30.32 to 50.52 g/plant and from 11.26 to16.91 g/plant respectively;fresh mass was allocated to different organs with the pattern of root <stem <leaf while dry mass was done with the pattern of root <leaf <stem as a whole.Water content of seedlings showed an increasing trend with height class,and the changing pattern of water content in different organs was as root <stem <leaf.Ratio of dry mass underground to aboveground in different classes was relatively constant.Quality index increased with height class valued as 1.018,1.121,1.208 and 1.239 respectively for four height classes with no significant differences between them.Morphological indices interrelated with each other,among which seedling height,ground diameter,fresh and dry mass and quality index reflected the comprehensive growth status of M.laosensis seedlings well and should be served as main indicators for evaluating and grading the seedlings.

Key words: seedling height, ground diameter, biomass, ratio of height to diameter, quality index