Hakusan Tree Is A (sinowilsonia) System Location Based On The Generalized Morphological Features

Sinowilsonia Hemsl., which has only one species, Sinowilsonia henryi Hemsl. ,belongs to the family Hamamelidaceae. The genus is endemic to middle temperate zone of China. The features of inflorescence and flower morphogenesis ,the variation of perforation plate of vessels, the contact ways between vessels and between vessel and xylem parenchyma cells or other cells, the organic anatomy and pollen features of Sinowilsonia Hemsl. were described in the present paper. Based on above research and related informations, we discussed the systematic position of Sinowilsonia Hemsl. in Hamamelidaceae. The observation results as follows:Morphogenesis and development of InflorescenceInflorescence of Sinowilsonia is unisexual. The male Inflorescence occur in the last of Jun or the first of Jul. It locate on the apex of stem, around it are there 3 phyllomes occur concomitantly. Later, it become column shape and the floral primordial occur acropetal on it helixly. In fore-and-aft October, the growth of male inflorescence ceased and it start live through the winter. In the last of Mar or the first of Apr of the next year, the inflorescence revival and continue growth until it become mature. The mature inflorescence is raceme , 2 cm long. The 3 phyllomes around the inflorescence growth to the mature leaf or fall off.The female Inflorescence primordial occur at the same time of the appearance of male Inflorescence primordial and they cannot be differentiate form their shape at this time. The development stage of female and male Inflorescence is very alike. The mature female Inflorescence is spike, 8cm long.Morphogenesis and development of Male flowersThe flower of Sinowilsonia is unisexual, monoecious. The whole male flower include bract, 2 bracteoles, 5 sepals, 5 petals and 5 stamens. The male flower primordial with the oval form occur on the male Inflorescence at its early development stage. The bract primordial is occur firstly on the male flower primordial, which locate on the abaxial of the flower primordial and have oval form. The 2 bracteoles occur in pairs in transverse position next. Later on, the bract and the 2 bracteoles primordial grow into triangular form and become recurved subsequently. After the occurrence of the bract and bracteoles, one sepal in adaxial position and the other two sepals in abaxial position occur simultaneity. Later, the remnant two adaxial sepals occur, which locate on the side of the first formed sepal. When the five sepals arrange as a whole and become recurved, the five petals alternated with the sepals occur as a whole simultaneity. Then, the quickly growing sepals cover the shortly formed petal primordials till it cover the entire flower.After the occurrence of petal primordials, the five stamen primordials in opposite position of the sepal primordials occur as a whole simultaneity. At this time, the flower apex become concave and the stamen primordials was covered by the sepals. Then, the stamen become ovate and the slowly growth petals can be seen at this time. Then, the stamen become recurved to the flower center and the petals grow into tiny protuberance in this time. The mature stamens have small anther and very short filaments. The anther with a very short connective protuberance have dorsal and ventral side and it is valvate dehiscence at maturity. The mature male flower have the rudiments of the opposite gender or not.Morphogenesis and development of Female flowersThe whole female flower include bract, 2 bracteoles, 5 sepals, 5 petals and 5 staminodes and two or three carpels. The carpel primordias initiated soon after the occurrence of stamen primordials. When the number of carpel is two, the crescent carpels primordias initiate on the flower apex opposite each other. Later, the carpel primordias become ovate in shape and the concave appears on its ventral side. At this time, the capel primordias begin conduplicate changes. Along with continuous conduplicate changes, the carpels differentition into style and stigma. The style grow quickly and become finger shape, at this time, the brim of conduplicate-carpels press each other and then syncretize into a short ovary. When the female flower become maturity, part of the sepals syncretize and form a calyx tube and the remains of sepals become calyx tooth. At this time, a cycle of staminodes could be seen around the base of gynoecia. The mature female flower have syncarpous but with long free styles, the calyx tube become kettle shape and is covered with stellate hairs, on the upside of the calyx tube are there five free calyx tooth. At this stage, the staminodes around the gynoecia differentition into anther and filaments and with a long connective protuberance. The surface of stigma of mature female flower is glabrous.When the number of carpel is three, the tuber like carpel primordias initiate simultaneously on the flower apex irregularly. The after development stage of three carpels is the same as the development stage of two carpels.Vessel Elements in Secondary XylemVessel is angular in transverse section, long and small in diameter. The end wall of vessel elements is mainly scalariform perforation plates, besides, there are also existing transitional types(also called scalariform-reticulate plates) which have bifurcate or fused or break bars. The lateral wall of vessel elements is mainly dense alternate pits and sparse pits, besides, there are also existing typical scalariform perforation plates in lateral wall. The pits and perforation plates in the lateral wall is the pathway linking the vessel elements and other cells, it is adapt in its function of transport the water and other materials.There are two contact types between vessel elements and other cells in xylem. One is the vessel elements contact each other; the other type is vessel elements contact the other cells(ray cells and parenchyma cells) in xylem. Vessel elements contact other cells in xylem through three types, there are: end walls contact each other; end walls contact lateral walls; lateral walls contact each other. Vessle elements contact each other by end wall perforation plates and lateral pits; vessel elements contact ray cells or parenchyma cells by lateral pits or lateral perforation plates.Anatomical StudiesThe seven vascular bundles in primary stem are arranged in a cycle, but they are separate from each other. The rays in the secondary wood are heterogeneous, multiseriate or uniseriate, and other structures are similar to most dicotyledon. The stem node is three traced and unilacunar. The vascular bundles of petiolar is separate-combine-separate form adaxial side to abaxial side , there are many vascular bundles separated at the base of petiolar and united like a horseshoe. The epidermic cells of leaf are irregular. The stomata of leaf is paracytic type and with several radial protuberances around it. The margin of leafe have gland-tooth, the teeth is fothergilloid type. The vine of leaf is pinnate type and its side vine have the second bifurcation vine. Stellate hairs cover the surface of leafe and other organs, the stellate hairs is developed from lateral and transverse divisions of the unicell protuberances on the surface of the organs. The structure of peduncle of male and female inflorescence is same as the structure of primary stem.Systematic PositionWe do the comparison and analysis of genera of Hamamelidaceae on the contents as follows: the floral morphogenesis and development; characters of vessel elements in secondary xylem; characters of the structure of the seed; geographical distribution and the morphologic and anatomy characters. Based on these datum, we consider that Sinowilsonia and Fortunearia and Eustigma are most related groups in Hamamelidaceae, in the groups, Sinowilsonia is more original than the other two, this conclusion is in accord with former results on the whole. But we must point out that some features of Sinowilsonia also show its speciality and isolation in the family of Hamamelidaceae.