湖北楠木屬一新變種
——裂葉白楠

孫 兵，肖 波，于鵬宇，潘 曉，費永俊

(長江大學 楠木種質資源評價及創新中心，湖北荊州 434025)

楠木是中國傳統珍貴林木，其材質精良、樹形優美，廣泛用于建筑、家具、雕刻和園林綠化[1-2]。長期以來，鑒于其巨大的經濟價值和廣泛的用途，野生楠木資源遭受嚴重破壞，現已難覓天然楠木林[3]。為了摸清湖北省野生楠木資源的現狀，作者承擔了全國第二次野生保護植物調查湖北調查-楠木專項調查任務，并于2012～2015年期間，完成了湖北省范圍內竹山[4]、竹溪、神農架[5]、興山、秭歸、長陽[6]、利川[7]、鶴峰、來鳳[8]、咸豐[9]、?？导扒G州周邊等縣市的楠木資源調查，對收集的白楠 [Phoebeneurantha(Hemsl.) Gamble] 種子進行異地播種保育，在約3萬株白楠幼苗中發現了100余株葉片發生變異的幼苗，栽培4年后開花結實，其種子萌發后植株葉片變異性狀穩定。通過查閱了相關文獻資料[10-12]，對比研究了葉片形態特征，確認系楠木屬植物的一個新類群，定名為裂葉白楠 [Phoebeneurantha(Hemsl.) Gamble var.lobophyllaY.J. Fei]，現予以報道。

1 裂葉白楠 新變種 (圖1)

Phoebeneurantha(Hemsl.) Gamble var.lobophyllaY.J. Fei, var. nov. (Fig.1.)

The new variety has some obvious characters. The leaf width was distinctly narrowed between the middle part of leaf and 1/3 from the tip of leaf. There are strong lateral veins supporting the leaf margins. The leaves were lobed, and if not, the leaves become narrowed. The two variants are narrowed and narrow in the apex. The apex part were leptophyllous, gradually pointed and curved in the two variants. The leaf was 10-23 cm in length, 2-5 cm in width and the base part was gradually narrowed. The veins fall deeper compared with thePhoebeneurantha.The angle between the lateral veins and the main veins increases gradually, and remains unchanged after about 80 degrees after the leaf blade becomes lobed and leptophyllous. At the same time, the lateral veins become more dense, the closer to the tip of the blade, the denser the lateral veins are, and the pinnate distribution. The number of unilateral veins varied from 8-12 to 25-40. The species are now stored in the Agricultural Science and Technology Industrial Park of Yangtze University, Jingzhou National Hi-tech Zone, Hubei.The seeds were collected from the subtropical evergreen deciduous broad-leaved mixed forest in the territory of the Tujia and Miao Autonomous Prefecture of Enshi, Hubei Province(E 108°23′12″-110°38′08″,N 29°07′10″-31°24′13″). Deciduous trees are dominant in broad-leaved trees. They are oftenChoerospondiasaxillaris,Camelliaoleifera,Platycaryastrobilacea,Castaneamollissima,Phyllostachysheterocycla,Iristectorum,Pileanotataand other plants.

本變種(裂葉白楠)與白楠(Phoebeneurantha)的主要區別在于：葉片中部到距葉尖約1/3葉長處葉片寬度陡然變窄，若有強健側脈支持則葉片發生裂刻，若無，葉片變狹長，且兩種變異均存在葉片先端變狹長，漸尖，呈彎鐮狀，葉長10-23 cm，中部葉寬2-5 cm，基部漸狹。相比于白楠，葉脈下陷更深。主葉脈在葉片開裂變狹后，側脈與主脈的夾角逐漸變大，大約80°左右后保持不變，同時側脈變得更加細密，越靠近葉尖側脈分布越密集，且呈羽狀分布。單側側脈數較白楠的8-12條變為25-40條不等?！?br>