Leaf Flushing as Taxonomic Evidenceof Some Diospyros Species (Ebenaceae)

Abstract

People tend to use generative structures for plant identification. Nevertheless, generative structure availibility limits the identification practice for a plant with once-a-year fruit-bearing-phase, such as Diospyros L. Being vegetative characters, leaf flushing are rarely used for plant identification so that they have not been explored as a taxonomic evidence. In this paper, leaf flushings and their taxonomic implication were studied using eight species of Diospyros grown in Ecopark of Cibinong Science Center LIPI, Bogor. This study explored Diospyros leaf flushing, including the following: 1) morphological developments, 2) phenology, 3) morphological variations, 4) taxonomic implication, and 5) phenetic relationships. Morphological and phenological data was observed on eight species of Diospyros with 22 qualified individual trees. Data obtained then descriptively and phenetically analized. Arrested growth in the development of Diospyros bud produce a rhythmic growth. After a dormant period, bud broke and produced a flushing set before finally back to its dormancy. Diospyros flushing set was usually distinguishable from the previous one by cataphyll scars at the twigs and the pattern of phytomer in a flushing set (leaf size, the length internodus and petiole), except on D. buxifolia which the phytomer was uniform and the cataphylls were very small and sometimes absent. Dorsal cataphyll only found in D. jaherii. The presence of small reduced leaf due to an arrested growth also can be used to indicate the base of flushing set in D. blancoi dan D. jaherii. The time of bud broken was not simultaneous in all Diospyros species, all individual trees within the same species, even in all buds of an individual tree under similar external condition. Diospyros have a seasonal growth pattern, except for D. jaherii. A mature flushing set was formed in 40-55 days. Leaves of Diospyros observed were arranged alternately and have equitant vernation. Leaf flushing provided 39 characters (included bud, young leaves, mature leaves, and flushing set characters) that can be used as taxonomic evidence for distinguishing eight species of Diospyros observed. A determination key for these species solely based on leaf flushing characters is presented. Dendrogram obtained showed that leaf flushing characters were capable to divide individuals observed as well as their species at the coefficient of similarity 76%. The most similar species were D. blancoi and D. celebica (74%). Both of them are belongs to subgenus Eudiospyros (L.) Bakh., section Ebenaster Bakh. The cophenetic correlation value obtained was 0,98 or very good fit (Rohlf 1998). Two principal coordinate analysis used shows the diversity of 26,79% and divided Diospyros into three groups. Group I contained D.malabarica, D. beccarioides, D. cauliflora and D. pilosanthera. Group II cotained D. blancoi, D. celebica dan D. jaherii. Group III contained D. buxifolia. Flushing characters seems to be varied and can be used as field identification of Diospyros observed. Thus, leaf flushing was proved capable as a taxonomic evidence for Diospyros species observed.