Departamento de Botánica, Instituto de Biología. Universidad Nacional Autónoma de México.
Ann Bot. 2011 Oct;108(5):847-65. doi: 10.1093/aob/mcr203. Epub 2011 Aug 17.
Within Chenopodioideae, Atripliceae have been distinguished by two bracteoles enveloping the female flowers/fruits, whereas in other tribes flowers are described as ebracteolate with persistent perianth. Molecular phylogenetic hypotheses suggest 'bracteoles' to be homoplastic. The origin of the bracteoles was explained by successive inflorescence reductions. Flower reduction was used to explain sex determination. Therefore, floral ontogeny was studied to evaluate the nature of the bracteoles and sex determination in Atripliceae.
Inflorescences of species of Atriplex, Chenopodium, Dysphania and Spinacia oleracea were investigated using light microscopy and scanning electron microscopy.
The main axis of the inflorescence is indeterminate with elementary dichasia as lateral units. Flowers develop centripetally, with first the formation of a perianth primordium either from a ring primordium or from five individual tepal primordia fusing post-genitally. Subsequently, five stamen primordia originate, followed by the formation of an annular ovary primordium surrounding a central single ovule. Flowers are either initially hermaphroditic remaining bisexual and/or becoming functionally unisexual at later stages, or initially unisexual. In the studied species of Atriplex, female flowers are strictly female, except in A. hortensis. In Spinacia, female and male flowers are unisexual at all developmental stages. Female flowers of Atriplex and Spinacia are protected by two accrescent fused tepal lobes, whereas the other perianth members are absent.
In Atriplex and Spinacia modified structures around female flowers are not bracteoles, but two opposite accrescent tepal lobes, parts of a perianth persistent on the fruit. Flowers can achieve sexuality through many different combinations; they are initially hermaphroditic, subsequently developing into bisexual or functionally unisexual flowers, with the exception of Spinacia and strictly female flowers in Atriplex, which are unisexual from the earliest developmental stages. There may be a relationship between the formation of an annular perianth primordium and flexibility in floral sex determination.
在藜科中，碱蓬族以两个包裹雌性花/果的小苞片为特征，而在其他族中，花被描述为无苞片，具有宿存的花被。分子系统发育假说表明“苞片”是同型的。小苞片的起源被解释为花序的连续减少。花的减少被用来解释性别决定。因此，研究了花的发育，以评估碱蓬族中苞片的性质和性别决定。
使用光学显微镜和扫描电子显微镜研究了滨藜属、藜属、猪毛菜属和菠菜属的物种的花序。
花序的主轴是不定的，具有基本的二歧花序作为侧单位。花以向心的方式发育，首先是花被原基的形成，要么来自一个环状原基，要么来自五个个体花被原基融合。随后，五个雄蕊原基起源，然后形成一个围绕中央单个胚珠的环状子房原基。花最初是两性的，保持两性和/或在后期阶段变为功能上的单性，或者最初是单性的。在所研究的滨藜属物种中，除了 A. hortensis 外，雌性花都是严格的雌性花。在菠菜中，雌性花和雄性花在所有发育阶段都是单性的。滨藜属和菠菜的雌性花被两个增大的融合的花被裂片保护，而其他花被成员缺失。
在滨藜属和菠菜中，围绕雌性花的修饰结构不是苞片，而是两个相反的增大的花被裂片，是宿存的花被的一部分。花可以通过许多不同的组合来实现性别；它们最初是两性的，随后发育成两性花或功能上的单性花，但菠菜和滨藜属中严格的雌性花除外，它们从最早的发育阶段就是单性的。环形花被原基的形成与花性别决定的灵活性之间可能存在关系。
