2种高山海棠营养器官的解剖结构及其生态适应性研究

Anatomical Characteristics of Vegetative Organs of Two Alpine Crabapples and Their Ecological Adaptation

采用NaOCl法、石蜡切片法对分布于海拔3 000 m的川西高原野生变叶海棠和花叶海棠的叶、茎、根进行了研究,旨在分析2种高山海棠营养器官的解剖构造,并探讨其解剖特征与川西高原干旱贫瘠地区的生态适应关系。结果表明:变叶海棠和花叶海棠的解剖构造极为相似,这可能与二者在起源及地理分布等的密切联系有关:二者叶的上下表皮细胞均具有厚的角质层,且上表皮气孔缺失、下表皮气孔密集,栅栏组织较厚,叶柄中具有分化出栅栏组织和海绵组织的纵棱脊结构;二者茎中的栓内层细胞壁较厚,次生木质部发达,导管周围分布着细胞壁木质化的木薄壁组织细胞,髓的外围有一圈细胞壁增厚的环髓带细胞;2种海棠的细根中已出现典型的次生结构,木质部占有极大的比例,主要以单管孔的形式存在的导管密集,无髓结构。变叶海棠和花叶海棠的上述解剖结构特征体现了二者对川西高原地区干旱环境都具有较强的适应能力。

The experiment was conducted to study the anatomical characteristics of alpine wild crabapples and their ecological adaptation, the vegetative organ structures of Malus toringoides and Malus transitoria from 3 000 m altitude in western Sichuan Plateau with paraffin sectioning and NaOCl. The two crabapples had similar anatomical structures. The possible reason might be their closed relationships of origins and geographic distribution between them. Both of the two plants had thick cuticle and epidermis cells. There was not stomata on the upper epidermis, while a dense stomata distribution was observed on the lower epidermis. The collateral vascular bundle was rich in palisade tissues on the lower epidermis. The longitudinal ridges structure with palisade and sponge tissues existed in the petiole. The phelloderm cells were crassexinous. The secondary xylem was rather rich in the stem. There were some wood parenchyma cells with lignified cell wall in the vicinity of the vessels. Around the pith there were crassexinous cells, called perimedullary zone. The secondary structure existed in the thin roots of both of the two crabapples, in which there was a large proportion of xylem and no pith. The vessels were dense, in the form of solitary pore. Therefore, the two alpine crabapples adapted well to the dry environment of western Sichuan Plateau.