孫 兵，肖 波，于鵬宇，潘 曉，費(fèi)永俊

(長(zhǎng)江大學(xué) 楠木種質(zhì)資源評(píng)價(jià)及創(chuàng)新中心，湖北荊州 434025)

楠木是中國(guó)傳統(tǒng)珍貴林木，其材質(zhì)精良、樹形優(yōu)美，廣泛用于建筑、家具、雕刻和園林綠化[1-2]。長(zhǎng)期以來(lái)，鑒于其巨大的經(jīng)濟(jì)價(jià)值和廣泛的用途，野生楠木資源遭受嚴(yán)重破壞，現(xiàn)已難覓天然楠木林[3]。為了摸清湖北省野生楠木資源的現(xiàn)狀，作者承擔(dān)了全國(guó)第二次野生保護(hù)植物調(diào)查湖北調(diào)查-楠木專項(xiàng)調(diào)查任務(wù)，并于2012～2015年期間，完成了湖北省范圍內(nèi)竹山[4]、竹溪、神農(nóng)架[5]、興山、秭歸、長(zhǎng)陽(yáng)[6]、利川[7]、鶴峰、來(lái)鳳[8]、咸豐[9]、?？导扒G州周邊等縣市的楠木資源調(diào)查，對(duì)收集的白楠 [Phoebeneurantha(Hemsl.) Gamble] 種子進(jìn)行異地播種保育，在約3萬(wàn)株白楠幼苗中發(fā)現(xiàn)了100余株葉片發(fā)生變異的幼苗，栽培4年后開花結(jié)實(shí)，其種子萌發(fā)后植株葉片變異性狀穩(wěn)定。通過查閱了相關(guān)文獻(xiàn)資料[10-12]，對(duì)比研究了葉片形態(tài)特征，確認(rèn)系楠木屬植物的一個(gè)新類群，定名為裂葉白楠 [Phoebeneurantha(Hemsl.) Gamble var.lobophyllaY.J. Fei]，現(xiàn)予以報(bào)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(qū)別在于：葉片中部到距葉尖約1/3葉長(zhǎng)處葉片寬度陡然變窄，若有強(qiáng)健側(cè)脈支持則葉片發(fā)生裂刻，若無(wú)，葉片變狹長(zhǎng)，且兩種變異均存在葉片先端變狹長(zhǎng)，漸尖，呈彎鐮狀，葉長(zhǎng)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(cè)脈與主脈的夾角逐漸變大，大約80°左右后保持不變，同時(shí)側(cè)脈變得更加細(xì)密，越靠近葉尖側(cè)脈分布越密集，且呈羽狀分布。單側(cè)側(cè)脈數(shù)較白楠的8-12條變?yōu)?5-40條不等。經(jīng)過對(duì)白楠葉緣和裂葉白楠缺刻處葉緣進(jìn)行電鏡掃描后發(fā)現(xiàn)，白楠葉緣下表面角質(zhì)化，表面較光滑，無(wú)毛；而裂葉白楠缺刻處葉緣下表面無(wú)角質(zhì)化，可明顯看出細(xì)胞排列結(jié)構(gòu)，且具毛。目標(biāo)物種現(xiàn)保存于湖北省荊州國(guó)家高新區(qū)長(zhǎng)江大學(xué)農(nóng)業(yè)科技產(chǎn)業(yè)園內(nèi)，種子采集于湖北省恩施土家族苗族自治州(E108°23′12″-110°38′08″，N29°07′10″-31°24′13″)境內(nèi)亞熱帶常綠落葉闊葉混交林中，闊葉樹種以落葉為主，林內(nèi)常有南酸棗(Choerospondiasaxillaris)、油茶(Camelliaoleifera)、化香(Platycaryastrobilacea)、栗樹(Castaneamollissima)、楠竹(Phyllostachysheterocycla)、鳶尾(Iristectorum)和冷水花(Pileanotata)等植物。

China，Hubei Jingzhou(湖北荊州)：Agricultural Science and Technology Industrial Park of Yangtze University(長(zhǎng)江大學(xué)農(nóng)業(yè)科技產(chǎn)業(yè)園)，alt.34 m,2016-8-3,Y.J.Fei,B.Sun,B.Xiao,P.Y.Yu,X.Pan(費(fèi)永俊，孫兵，肖波，于鵬宇，潘曉)Y.J.Fei002(HIB)(Holotype，HIB)，見圖1。

2 討 論

世界楠屬植物共約有94種，中國(guó)分布的約有34種[13]，均是中國(guó)珍稀瀕危植物，素以材質(zhì)優(yōu)良、形態(tài)優(yōu)美而聞名于世[12]。楠屬植物葉片常為披針形、卵圓形或橢圓形，葉片互生，革質(zhì)，分類的主要參照是葉片形態(tài)、果實(shí)形態(tài)、葉脈下陷情況以及花被、花序及葉片有無(wú)被毛等特點(diǎn)[12]。根據(jù)《中國(guó)植物志》[13]中有關(guān)白楠的記載，目前發(fā)現(xiàn)白楠有2個(gè)變種：興義白楠 [Phoebeneurantha(Hemsl.) Gamble var.cavalerieiLiou]和短葉白楠 [Phoebeneurantha(Hemsl.) Gamble var.brevifoliaH.W.Li]。其中，興義白楠的典型特征為：葉片狹小，長(zhǎng)4.5-7.5 cm，寬1-2 cm，中脈在上面凸起。而短葉白楠的特征為：葉片倒卵形或倒卵狀披針形，長(zhǎng)3-11 cm，先端鈍。這2個(gè)白楠變種的葉片長(zhǎng)度均小于白楠，且無(wú)裂刻出現(xiàn)。本文報(bào)道的裂葉白楠與白楠存在明顯的區(qū)別：中部到距葉尖約1/3葉長(zhǎng)處陡然開裂分叉，或者無(wú)明顯缺刻但葉片變狹長(zhǎng)，兩種變異均存在葉片先端變狹長(zhǎng)，呈彎鐮狀；葉脈下陷程度更高，在葉片尖端側(cè)脈數(shù)較多較細(xì)，與主脈夾角變大，呈羽狀排列；裂刻處葉緣無(wú)革質(zhì)化且具細(xì)毛。且這些差異性狀能夠在子代間穩(wěn)定遺傳。同時(shí)，本文報(bào)道的裂葉白楠，葉片特征與興義白楠和短葉白楠也同樣存在明顯差異。給予上述理由，將其定為白楠的一個(gè)新變種——裂葉白楠。