全 文 ：植物学报 Chinese Bulletin of Botany 2011, 46 (5): 489–497, www.chinbullbotany.com
doi: 10.3724/SP.J.1259.2011.00489
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收稿日期: 2011-04-20; 接受日期: 2011-05-16
基金项目: 中国博士后科学基金(No.20080440556)
* 通讯作者。E-mail: qijiangxu@ibcas.ac.cn
基部被子植物雪香兰(金粟兰科)单性花的形态发生和发育
崔永坤1, 徐启江1, 2*, 孙永华1, 孟征1
1中国科学院植物研究所信号转导与代谢组学研究中心, 北京 100093
2东北林业大学生命科学学院, 哈尔滨 150040
摘要 基部被子植物金粟兰科(Chloranthaceae)的单性花或两性花结构十分简单, 雪香兰(Hedyosmum orientale)花单
性、雌雄异株, 花的形态及结构与其它属物种具有显著的差异, 对于研究被子植物花特别是花被的起源和系统进化具有重
要意义。该研究采用电子显微镜和光学显微镜观察了雪香兰单性花的器官发生及发育过程。结果表明, 雌、雄花均为顶生
和腋生, 多个小花呈聚伞圆锥状排列。雄花外侧是苞片, 每朵雄花上着生150–200个雄蕊, 花轴基部着生少数退化的叶原
体。苞片原基及其腋生的花原基最初呈圆丘状, 随后伸长。在雄花发育过程中, 苞片原基比雄蕊原基生长快, 雄花原基纵向
伸长, 叶原体原基在基部发生, 雄蕊原基自下而上发生。每2朵雌花底部合生形成小聚伞花序, 每朵雌花被一苞叶包裹, 由
单心皮和三棱型子房构成, 外覆三裂叶状花被。在雌花发育过程中, 雌花原基比苞片原基生长快, 花被原基首先于花顶端发
生, 随后花顶端中心凹陷, 进一步发育成具有单心皮的子房原基。雪香兰的单性花发育不经过两性同体阶段, 花分生组织只
起始雄蕊器官或雌蕊器官的发育。研究结果支持雪香兰单性花是原始性状的观点, 雄花叶原体与雌花三裂叶状花被同源,
可能是花被(萼片与花瓣)的起源。
关键词 金粟兰科, 花器官发生, 雪香兰, 单性花
崔永坤, 徐启江, 孙永华, 孟征 (2011). 基部被子植物雪香兰(金粟兰科)单性花的形态发生和发育. 植物学报 46, 489–497.
被子植物即显花植物是植物界中进化最高级、种
类最多、分布最广的类群 , 约有35万种 (Litt and
Kramer, 2010)。花是被子植物的重要生殖器官, 也是
被子植物特有的创新性状, 其形态多样性是鉴定被子
植物科、属、种关系最可靠的外部特征。然而, 我们
对于花的起源及其多样性的形成还知之甚少, 科学家
一直被有花植物的短期快速分化及其丰富的多样性
所困惑 , 达尔文称之为“讨厌之谜” (abominable
mystery)(李贵生等, 2003; Friedman, 2009)。被子植
物具有两性花(完全花)或单性花(不完全花)等多样性
的有性生殖系统(Tanurdzic and Banks, 2004)。大多
数被子植物能够形成兼具雄性功能和雌性功能的两
性花, 但也有大约30%的种类会产生只具雄性功能或
雌性功能的单性花(Richards, 1997)。从个体或群体
角度 , 可以界定被子植物的性别状态(Cruden and
Lloyd, 1995; Neal and Anderson, 2005), 如雌雄同
体(hermaphrodite)、雌雄同株(monoecism)、雌雄异
株(dioecism)、雌花两性花异株(gynodioecism)和雄
花两性花异株(androdioecism)等。其中雌雄异体在被
子植物中大约只占6%(Renner and Ricklefs, 1995),
并且这些单性花物种分布于被子植物不同进化分支
上的事实表明, 不同物种的雌雄异花性可能是通过不
同的机制而独立进化形成的 (Mitchell and Diggle,
2005)。性别分离是促进异交、保持遗传多样性的重
要途径, 其进化机制正日益受到生物学家的关注。
金粟兰科(Chloranthaceae)是被子植物最基部的
类群之一(Qiu et al., 2006), 由于其简单的花结构、原
始的花粉特点以及较为久远的化石记录而引起人们
的关注 (Swamy and Bailey, 1950; Burger, 1977;
Leroy, 1983; Endress, 1987)。该科现存4个属: 金粟
兰属(Chloranthus)和草珊瑚属(Sarcandra)具有两性
花和虫媒传粉的相关特征, 其花无花被, 仅由1枚雄
蕊和1枚心皮构成, 是被子植物中最简单的两性花;
雪香兰属(Hedyosmum)和Ascarin具有单性花和风媒
传粉的相关特征, 雄花具1枚雄蕊, 雌花具1枚心皮
(Endress, 1987; Todzia, 1988; Luo and Li, 1999;
·研究论文·
490 植物学报 46(5) 2011
Tosaki et al., 2001), 是被子植物中最简单的单性花。
雪香兰属主要分布于热带美洲 (Verdcourt, 1985;
Todzia, 1988), 我国只有 Hedyosmum orientale
Merr. et Chun 1种(Chen et al., 1997), 其花单性、雌
雄异株、雌花具花被(Endress, 1987; Todzia, 1988)。
由于雪香兰属花结构简单且与最早的单性花化石相
似(Friis et al., 2006), 因此被认为是被子植物与买麻
藤目植物之间的联系纽带(Taylor and Hickey, 1992;
Nixon et al., 1994), 为开展被子植物花发育研究提
供了一个模型, 在探讨被子植物(花)起源和早期进化
方面具有重要价值。但是分子系统学分析表明, 与
ANITA类 群 (Amborellaceae, Nymphaeaceae, Il-
liciales, Trimeniaceae和Austrobaileyales)相比 , 金
粟兰科是较进化的分支(Qiu et al., 2006), 暗示金粟
兰科植物的花并不是被子植物的原始类型, 而是发生
了进化简约 (evolutionary reduction)(Doyle et al.,
2003; Frohlich and Chase, 2007)。
关于雌雄异花物种的性别分化, 从形态发生和发
育过程而言, 有2条单性花的形成途径。一条途径是
所有的花器官原基均能够发生并起始发育, 但性器官
之一在随后的发育阶段退化或败育(Heslop-Harrison,
1964; Uhl, 1972; Sherry et al., 1993)。此途径被称为
I型单性花发育模式(Mitchell and Diggle, 2005), 又
分为2种情况(Matsunaga and Kawano, 2001): 异性
原基的发育在早期阶段受到抑制 , 如玉米 (Zea
mays)(Cheng et al., 1983); 或在花发育的晚期表现
出来, 即异性器官在晚期阶段的发育受到抑制, 如葡
萄(Vitis vinifera)雄花的心皮由于胚囊的败育而不育
(Caporali et al., 2003), 薄叶棕竹(Rhapis subtilis)雌
花形成的原因是由于花药不能产生花粉(Dransfield
et al., 2008)。另一途径是花发育过程绕过雌雄同体发
育阶段, 特定生殖器官原基根本就没有发生, 即在雄
花中没有心皮原基的形成, 同样在雌花中也没有雄蕊
原基的形成。这类单性花的形成途径被称为II型单性
花发育模式, 如菠菜(Spinacia oleracea)(Sherry et
al., 1993)。大多数雌雄异花物种是通过第1条途径形
成单性花的, 如酸模(Rumex acetosa)(Ainsworth et
al., 1995)、白麦瓶草(Silene latifolia)(Janoušek et al.,
1996; Farbos et al., 1997)、黄瓜(Cucumis sativus)
(Kater et al., 2001)、芦笋 (Asparagus officinalis)
(Park et al., 2003)和桃花心木 (Swietenia macro-
phylla)(Gouvêa et al., 2008)。对花发育形态学过程
的观察不仅能够展现花器官发育的时空特性, 还可鉴
定新的形态学特征, 揭示花部结构的同源性, 为植物
系统发育分析提供直观证据。在金粟兰科植物中, 有
关花发育形态学特性的研究仅限于金粟兰属、草珊瑚
属和Ascarin属(Leroy, 1983; Endress, 1987; Kong
et al., 2002; Doyle et al., 2003), 有关雪香兰属花的
研究只限于对花外部形态特征的描述, 而对于花器官
发生和发育的系统研究尚未见报道。本研究以中国海
南岛雪香兰(Hedyosmum orientale Merr. et Chun)为
材料, 对其雌雄花解剖学特征和单性花器官发生途径
进行了系统研究, 探讨了花器官发生和发育的系统分
类学意义, 以期为研究被子植物花器官(特别是花被)
的起源和进化提供实验资料。
1 材料与方法
1.1 材料
雪香兰(Hedyosmum orientale Merr. et Chun)雌雄
株活体材料于2008年2月和2009年2月采自海南省陵
水黎族自治县吊罗山区(18°41′N–18°44′N, 109°50′E–
109°55′E), 凭证标本为Cui YK et al. Female(HLD)
08-02、Cui YK et al. Male(HLD)08-02、Cui YK et al.
Female(HLD)09-02和Cui YK et al. Male(HLD)09-
02。选取雌雄株上不同发育时期的花序和花蕾用于解
剖学观察。
1.2 方法
取材与固定: 将选取的雌雄花序和花芽立即用FAA
(formalin-acetic acid-alcohol)固定液(37%福尔马林:
乙酸:70%乙醇=5:5:90)固定, 置于抽真空机(Eppen-
dorf Vacufuge Concentrator 5301)内抽气15–30分
钟, 直到材料完全沉降至容器底部。更换FAA固定液
后于4°C条件下固定16小时, 50%、70%梯度乙醇脱
水, 更换70%乙醇后于4°C保存备用。
电子显微镜观察: 将在70%乙醇中保存的材料转
入 95%乙醇中脱水 , 在立体解剖显微镜 (LEICA
S8APO)下解剖花芽, 用LEICA DFC300FX数字彩色
图像照相机拍照。对解剖材料进行100%乙醇脱水及
系列梯度乙酸异戊酯置换处理后, 用JFD-310二氧化
碳临界点干燥仪(HITACHI, 日本)冷冻干燥、JEC-1600
崔永坤等: 基部被子植物雪香兰(金粟兰科)单性花的形态发生和发育 491
离子溅射仪(JEOL, 日本)喷金, 在HITACHI S-800扫
描电子显微镜下观察(加速电压15 kV)和照相。
2 结果与分析
2.1 雌雄花序及单性花形态
Hedyosmum orientale Merr. et Chun为雌雄异株, 雄
花腋生与顶生, 长5–8 cm、具有2个对生苞片, 成熟
雄花的花梗较长。1朵顶生雄花和2朵腋生雄花构成复
合穗状花序(spike), 各穗状花序呈聚伞圆锥状排列
(图1A)。每个穗状雄花上着生150–200个螺旋状排列
的无丝雄蕊(图1B)。花药4室、长约0.5 cm, 卵状椭圆
形、表面具4条纵沟(图1D); 纵向开裂、药隔顶部融合
延伸外突且先端锐尖(图1D, E)。花轴基部着生少数退
化的叶原体(phyllome)(图1C)。
雌花腋生与顶生, 构成聚伞圆锥花序(thyrse)(图
1F)。花轴上着生数个叶原体, 多朵雌花底部簇生或边
缘重叠呈覆瓦状而形成小聚伞花序(cymule)(图1G),
小聚伞花序内每2朵雌花的底部合生(图1H)。雌花均
被一大苞片包裹(图1I), 由单心皮和三棱型子房构成、
外覆顶部三裂叶状花被(图1G)。花被下半部分融合成
杯状、顶部三裂叶状分开、边缘弧形, 柱头从位于花
被片之间的子房顶部伸出、呈不规则的裂片状(图1J)。
2.2 花器官的发生与发育
2.2.1 雄花的发育
在雪香兰植株顶部及各叶腋处, 营养顶端转化为生殖
顶端 , 雄花花序分生组织开始形成 , 呈圆丘状(图
2A)。随后叶腋处雄花原基伴随着苞片原基的出现而
形成(图2B), 雄花原基和苞片原基同时进行纵向伸长
生长, 两者因细胞分裂而相互挤压(图2B, C)。但是雄
花原基在发育过程中继续保持山丘状, 不断向上隆
起; 而苞片原基横向生长增快、顶部钝突尖, 基部包
围发育过程中的雄花原基(图2D)。叶原体原基首先在
雄花原基的周围发生(图2E–G)。叶原体原基持续分
化、生长而形成一条顶端波形带状隆起(图2H–J)。随





图1 雪香兰雌雄异株花序及花形态
(A) 雄花花序, 每个穗状雄花具有2个苞片; (B) 单个穗状雄花, 上有150–200个雄蕊螺旋状排列; (C) 穗状花轴底部的叶原体, 雄蕊
衰老脱落; (D) 裸露雄蕊; (E) 雄蕊药隔融合外突2–3 mm, 先端锐尖; (F) 雌花花序; (G) 雌花聚伞圆锥花序, 每朵雌花具有包裹子房
的三裂叶状花被; (H) 雌花花芽, 2朵雌花组成小聚伞花序, 雌花具苞片; (I) 成熟的雌花; (J) 羽毛状柱头。br: 苞片; ec: 外突药隔;
ph: 叶原体; pe: 花被; sti: 柱头。(A), (F) Bar=3 cm; (B), (I) Bar=1 cm; (C), (D), (H) Bar=5 mm; (E), (J) Bar=2 mm; (G) Bar=2 cm

Figure 1 The unisexual inflorescence and floral morphology of dioecious Hedyosmum orientale
(A) Male inflorescence, the staminate flower is subtended by two leaf-like bracts; (B) Staminate flower showing 150–200 sta-
mens spirally arranged along the spike axis; (C) The phyllome at the base of the floral axis observed during stamen senescence
and separation from the spike axis; (D) Stamens of the male flower; (E) The terminal connective extension is extended 2–3 mm
beyond the thecae into an acute upwardly projecting apicule; (F) Female inflorescence; (G) The female compound thyrse
(Close-up of a figure with female flower showing the three perianth lobes at the top, making the ovary inferior); (H) Young female
flower buds, two flowers clustered into a cymule with the adjacent floral bracts (one per flower); (I) Mature female flowers; (J)
Plumose stigma. br: Bract; ec: Extended connective; ph: Phyllome; pe: Perianth; sti: Stigma. (A), (F) Bar=3 cm; (B), (I) Bar=1 cm;
(C), (D), (H) Bar=5 mm; (E), (J) Bar=2 mm; (G) Bar=2 cm

492 植物学报 46(5) 2011



图2 雪香兰雄花发育的电子显微镜及体视显微镜图像
(A) 圆丘状花序分生组织发生; (B)–(D) 雄花原基与苞片原基发生; (E)–(G) 雄花原基纵向伸长, 同时伴有叶原体原基发生和发育;
(H)–(J) 雄蕊原基发生和发育; (K) 雄蕊原基自下至上逐渐发育成熟; (L) 叶原体形成; (M) 成熟的雄蕊; (N) 雄蕊药隔延伸外突结
构。bp: 苞片原基; im: 花序原基; mfp: 雄花原基; pp: 叶原体原基; ph: 叶原体; sp: 雄蕊原基。Bar=100 μm

Figure 2 Scanning electron microscopy and stereo microscope photos of staminate flowers of Hedyosmum orientale
(A) Initiation of inflorescence meristem as a mound of undifferentiated cells; (B)–(D) Initiation of male floral primordium and bract
primordium; (E)–(G) Male floral primordium expands longitudinally and the phyllome primordia are established; (H)–(J) Initiation
of staminate primordial, and developing stamen primordia begin to assume a knoll shape in the rhachis; (K) Further development
of stamen primordium at the axis from bottom to top; (L) Phyllome formation; (M) Mature stamens; (N) Extended connective. bp:
Bract primordia; im: Inflorescence meristem; mfp: Male floral primordium; pp: Phyllome primordial; ph: Phyllome; sp: Staminate
primordia. Bar=100 μm



着雄花原基的发育, 在叶原体原基上方、雄花原基基
部发生雄蕊原基(图2H–K), 并由下至上渐次发生, 雄
花的各个雄蕊呈穗状排列(图2K)。与雄花原基相比,
叶原体原基生长较慢且横向生长量大于纵向(图2L)。
雄蕊自基部向上渐次发育成熟(图2M); 雄蕊顶部锐
尖, 是药隔顶部融合延伸外突形成的结构(图1E; 图
2N)。在雄花发育过程中没有花被原基的发生。

2.2.2 雌花的发育
同雄花一样, 雪香兰雌花顶生及腋生。当营养茎端转
换为生殖茎端后, 在随后的发育过程中其周围的分生
组织不断分化形成苞片原基, 在苞片原基的叶腋处产
生雌花原基, 发育的苞片原基和雌花原基由于紧密相
邻而互相挤压, 致使半圆球状原基发生细微变形(图
3A)。苞片原基发育膨大迅速、纵向生长量大, 先端
向雌花原基一侧弯曲并越过雌花原基顶部(图3B, C),
持续进行向性生长似鱼钩形(图3D); 弯曲的苞片原基
基部逐渐变宽, 发育成型的苞片基部似帽子形状包裹
着整个雌花(图1I)。雌花原基在发育过程中伴随着花
被原基的出现而由半圆球形向三棱柱形转化 (图
3D–F)。继花被原基分化后, 花原基顶部中央出现心
皮原基, 心皮原基的发育过程是首先花原基顶端中央
组织逐渐凹陷形成狭缝, 然后狭缝周围的中央组织向
上突起分化形成单心皮原基(图3F)。花被原基和心皮
原基继续发育, 但花被原基生长速度较快, 将雌蕊包
裹其内(图3G–I), 所以雪香兰雌花为子房周位花。花
被顶部呈三裂叶状、近圆弧形, 基部无节(Endress,
2008)。花被组织一般在贴生子房的顶部及3个脊部生
长速度较快, 导致子房3个正面的花被组织较薄, 形
成3个小孔洞状的凹陷(图3J, K)。Endress(1971)认
为, 孔洞形成的原因是子房脊部的花被组织没有向子
房正面延伸生长, 而不是花被组织细胞裂生的结果
(DArcy and Liesner, 1981)。在本实验中, 我们观察
到了子房脊部与顶部花被组织向内生长、逐渐融合及
孔洞状凹陷消失的情况(图3L), 这证实了Endress推
测的正确性。随后子房进一步发育, 花柱开始生长,
崔永坤等: 基部被子植物雪香兰(金粟兰科)单性花的形态发生和发育 493



图3 雪香兰雌花发育的电子显微镜及体视显微镜图像
(A) 圆丘状雌花分生组织及苞片原基起始; (B), (C) 花原基膨大, 呈椭圆形凸起, 苞片原基生长迅速; (D) 苞片弯曲; (E) 花被原基;
(F) 心皮原基起始发育; (G)–(I) 花被与心皮生长膨大(箭头示心皮原基中央出现凹陷的小窝); (J), (K) 三裂叶状花被(箭头示在子房
壁正面形成的孔洞状结构); (L), (M) 心皮分化出花柱和柱头(箭头示花被的孔洞状凹陷融合); (N) 柱头从三裂花被间隙中伸出; (O)
乳突细胞。bp: 苞片原基; cp: 心皮原基; ffp: 雌花原基; sti: 柱头; sty: 花柱; tpp: 三裂花被原基。Bar=100 μm

Figure 3 Scanning electron microscopy and stereo microscope photos of female flowers of Hedyosmum orientale
(A) Initiation of female floral meristem and bract primordium; (B), (C) Floral primordium bulges and turns ellipsoid-shaped, and
the bract primordium continues growing and developing quickly; (D) Hooked bract; (E) Trifid perianth primordium is established in
the periphery of floral meristem; (F) Carpel primordium is formed in the space between the trifid perianth primordium; (G)–(I)
Perianth primordium has expanded both laterally and longitudinally and has surrounded the carpel primordium (The arrows in-
dicate a locule occurring in the center of carpel primordium); (J), (K) Perianth is attached to the ovary only along the three ridges
and the top of the ovary and is free over the three faces (The arrows indicate that three pores are formed); (L), (M) Style and
stigma have differentiated (Style is short and hidden in the ovary, and the arrow indicates the perianth fused by the tissue ema-
nating from the ridges of the ovary in some female flowers); (N) Stigma extends out from the top of the ovary between the peri-
anth lobes; (O) Stigma papilla cells. bp: Bract primordia; cp: Carpel primordium; ffp: Female floral primordium; sti: Stigma; sty:
Style; tpp: Trifid perianth primordium. Bar=100 μm


柱头逐渐从三裂花被之间伸出(图3L, M); 花柱较短、
深埋在雌花内, 柱头羽毛状(图3N), 干性乳突细胞呈
长圆形(图3O)。
3 讨论
以往的研究已经发现了与金粟兰科有亲缘关系的白
垩纪植物化石, 但是人们对金粟兰科植物简单花器的
起源有不同的观点, 即进化简约(Walker and Walker,
1984)和原始性状(Leroy, 1983)。分子系统进化分析
结果表明 , ‘ANITA’是现存被子植物的最原始类群
(Qiu et al., 1999), 从花结构来看, ANITA类群的花一
般具有花被、数个雄蕊和心皮(Trimenia只有1个心
皮)。而金粟兰科植物花的结构比较简单, 除雪香兰属
的雌花具有三裂叶状花被外 , 均为裸花、1枚雄蕊
(Ascarina属的部分种具有2–5枚雄蕊)、1枚心皮。因
此Doyle等(2003)、Frohlich和Chase(2007)认为, 金
粟兰科植物的花并不是最原始的, 而是发生了进化简
494 植物学报 46(5) 2011
约。但是Leroy(1983)认为, 雪香兰属雄花并不是单雄
蕊、裸露、无苞被的花, 其穗状雄花序实质上是一朵
雄花, 由数百枚雄蕊在轴上螺旋状排列组成, 十分类
似于裸子植物的雄球花, 是一种原始性状。我们的研
究结果似乎为Leroy的观点提供了证据: 雄花原基伴
随着苞片原基的产生而出现(图2A–D)。这种情况同样
出现在雌花的发育过程中, 雌花原基与苞片原基同时
形成(图3A–D), 只是2类苞片原基的发育特点有所差
异。雄花苞片原基的发育速度慢于雄花原基的发育;
而雌花苞片原基的发育速度快于雌花原基的发育, 但
2类苞片原基均表现出弯向花原基的极性生长特点。
在苞片原基发育以后, 雄花原基上继而出现叶原体原
基(图2E–G), 然后自下而上逐渐分化出雄蕊原基(图
2H–L), 类似焕镛木 (Woonyoungia septentrionalis
(Dandy) Law)(木兰科Magnoliaceae)的雄蕊发育特
征(Fu et al., 2009)。我们认为雪香兰的雄花由基部的
叶原体和数百枚螺旋状排列的雄蕊构成, 其中雄花叶
原体可能与雌花的三裂叶状花被同源。因此, 我们认
为雄花的穗状结构应该是一朵花而不是Endress
(2001)所认为的花序。雄花叶原体发育缓慢、个体小
于雄蕊可能是对风媒传粉的一种适应性。
我们的形态学和胚胎学观察结果表明, 雪香兰的
花发育符合II型单性花发育模式, 即花分生组织只起
始雄蕊器官或雌蕊器官的发育, 不经过两性同体阶
段。而Ascarina属一些物种的雄花发育符合I型单性花
发育模式, 在雄花发育过程中可观察到败育心皮的发
生(Doyle et al., 2003)。雪香兰单性花的产生是由于
异性器官发育起始的缺失而不是由于异性器官的败
育, 即雄花缺失雌蕊原基, 雌花缺失雄蕊原基。根据
花器官发育的ABC模型 (Coen and Meyerowitz,
1991), 各个花器官原基的发生是由同源异型MADS-
box基因控制的。研究发现, 在同为II型单性花发育模
式的雌雄异株唐松草(Thalictrum dioicum)(Di Stilio
et al., 2005)和菠菜(Pfent et al., 2005; Sather et al.,
2005, 2010)中, B类和C类MADS-box旁系同源基因
(paralogue)在雄花或雌花中的表达模式发生了变化。
我们从雪香兰中克隆了B类MADS-box基因HoAP3和
HoPI, 实时定量RT-PCR分析结果表明, HoAP3在雄
花中特异表达; 而HoPI-1、HoPI-3在雌、雄花中均表
达, 但HoPI-2只在雄花中弱表达, 说明花器官同源异
型MADS-box基因确实参与了雪香兰单性花发育的
性别决定(未发表资料)。在整个被子植物类群中, 雌
雄异株独立进化了100多次 (Grant et al., 1994;
Charlesworth, 2002), B类和C类MADS-box基因在调
控被子植物性别二态性方面的功能也必然会发生变
化。由于雪香兰属于基部被子植物, 因此深入开展对
花器官同源异型MADS-box基因重复、功能趋异和活
性模式建立的分子事件的研究, 阐明雪香兰花部性状
雌雄异形的分子遗传机制, 可为花器官身份基因进化
与花器官属性决定的关联研究提供线索。
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崔永坤等: 基部被子植物雪香兰(金粟兰科)单性花的形态发生和发育 497
Characterization of Unisexual Flower Development in the Basal
Angiosperm Hedyosmum orientale (Chloranthaceae)
Yongkun Cui1, Qijiang Xu 1, 2*, Yonghua Sun1, Zheng Meng1
1Center for Signal Transduction and Metabolomics, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
2College of Life Science, Northeast Forestry University, Harbin 150040, China
Abstract Chloranthaceae are a family of basal angiosperms with very simple unisexual or bisexual flowers. Hedyos-
mum orientale Merr. et Chun is a dioecious species with unisexual flowers. The floral morphology and structure of H.
orientale conspicuously differ from that of other species and are important in the study of floral origin and phylogeny,
especially of the perianth, in angiosperms. We investigated the organogenic processes and anatomical characters related
to unisexual flower development in H. orientale Merr. et Chun by scanning electron and light microscopy. Male and fe-
male flowers are in the axil of bracts and are usually formed in a thyrse. The staminate flower is subtended by two leaf-like
bracts. 150–200 stamens spirally arranged along the spike axis and the phyllome are located at the base of the spike axis.
The bract primordium with its axillant flower primordia is dome-shaped in the beginning and then elongates. The bract
primordium grows faster than the floral primordium during male flower development. The male floral primordium expands
longitudinally and the phyllome primordia are established around the base. Stamen primordia are formed and further
develop at the axis from bottom to top. Two female flowers, composed of trifid perianth and inferior ovary, cluster into a
cymule with the adjacent floral bracts. The floral primordium grows faster than the bract primordium during the female
floral development process. Three perianth primordia are initiated along the sides of the trilateral floral apex. Simultane-
ously, a concave floral apex appears, which differentiates into an ovary primordium. The floral development of H. orien-
tale Merr. et Chun is unisexual from inception. The floral meristem initiates only androecial or gynoecial organs and does
not go through a hermaphroditic stage. Our studies support the view that the flower of H. orientale Merr. et Chun is a
primitive character. The trifid perianth of the female flower is homologous to the phyllomes at the bottom of the male
flower. They may be the origin of the perianth (sepal and petal).
Key words Chloranthaceae, floral organogenesis, Hedyosmum orientale, unisexual flower
Cui YK, Xu QJ, Sun YH, Meng Z (2011). Characterization of unisexual flower development in the basal angiosperm
Hedyosmum orientale (Chloranthaceae). Chin Bull Bot 46, 489–497.
———————————————
* Author for correspondence. E-mail: qijiangxu@ibcas.ac.cn
(责任编辑: 刘慧君)