กายวิภาคศาสตร์ใบและสัณฐานวิทยาเรณูของพืชสกุลตําหยาว (วงศ์กระดังงา) ในประเทศไทย

Abstract

Leaf epidermal anatomy and pollen morphology of the genus Alphonsea Hook.f. & Thomson in Thailand were studied. The comparative anatomy of leaf in 15 species by the peeling method. The common characteristics are as follows: There are two types of epidermal cell shape are amorphous with sinuate anticlinal walls and jigsaw-like with cleft concave anticlinal walls. Two stomatal types are paracytic and para-tetracytic. Stomatal length ranges from 21.15±1.69 to 26.85±2.30 micrometers. The stomatal density varies from 155.00±23.21 to 373.00±88.58 stomata per area. The stomatal index varies from 12.60±1.87 to 19.41±0.77%. Two types of crystal are druse and prismatic crystal. One type of hair is multicellular, which is found in most species of uniseriate hair. The comparative anatomy of the leaf by paraffin technique of the leaf blade and petiole is as follows: most of the plants that were examined have one cell layer in the upper epidermis. Only one species has 1-2 cell layers. The height of a cell ranges from 12.50 to 42.50 micrometers. The epidermal cell of the midrib of most plants has 1-2 cell layers; six species have only one cell layer. The height of a cell ranges from 5.00-37.50 micrometers. There is only one cell layer on the lower epidermis of the leaf blade and midrib. Leaf blade: the height of a cell ranges from 17.50 to 12.50 micrometers. Midrib: the height of a cell ranges from 5.00 to 12.50 micrometers. Two types of leaf margins are curve downward and straight leaf margins. All the plants studied had thick cuticles. Vascular tissue is a collateral vascular bundle. An overview of the vascular bundle has two characteristics are viewed in a heart-like and semicircular shape. Four types of petiole shape in cross section are terete, cordate, semi-terete, and butterfly-like. The pollen morphology of 14 species in the genus Alphonsea were observed by using light and scanning electron microscopes. The common characters of pollen are monad, apolar, radial symmetry and inaperturate. The length of the average diameter is between 41.00±1.75 to 50.00±3.33 micrometers. The shape of pollen is spheroidal. The exine is thick and ranges 1.38±0.40 to 3.50±1.29 micrometers. Three types of exine ornamentation are fossulate, rugulate, and fossulate mixed with scabrate. This study revealed the following results: the leaf anatomy of the genus can help identify species with similar external morphology. Study of the pollen morphology of plants in this genus cannot be clearly identified the species level, although a pattern on exine ornamentation can be used to classify plants into 3 groups. Therefore, the investigation of leaf anatomy and pollen morphology in the genus Alphonsea in Thailand can be applied to support the taxonomic and other studies into more complete knowledge.