Royal Botanic Gardens, Kew, Jodrell Laboratory, Richmond, Surrey TW9 3DS, UK.
Ann Bot. 2013 Nov;112(8):1567-76. doi: 10.1093/aob/mcs258. Epub 2012 Dec 12.
The inflorescence structure determines the spatiotemporal arrangement of the flowers during anthesis and is therefore vital for reproductive success. The Leguminosae are among the largest angiosperm plant families and they include some important crop plants. In papilionoid legumes, the raceme is the most common type of inflorescence. However, a range of other inflorescence types have evolved via various developmental processes. A (re-)investigation of inflorescences in Swainsona formosa, Cicer arietinum, Abrus precatorius, Hardenbergia violacea and Kennedia nigricans leads to new insights into reduction mechanisms and to a new hypothesis on the evolution of the papilionoid pseudoraceme.
Inflorescence morphology and ontogeny were studied using scanning electron microscopy (SEM).
The inflorescence in S. formosa is an umbel with a rare type of pendulum symmetry which may be triggered by the subtending leaf. Inflorescences in C. arietinum are reduced to a single flower. An early formed adaxial bulge is the sterile apex of the inflorescence (i.e. the inflorescence is open and not terminated by a flower). In partial inflorescences of A. precatorius, the axis is reduced and its meristem is relocated towards the main inflorescence. Flower initiation follows a peculiar pendulum pattern. Partial inflorescences in H. violacea and in K. nigricans show reduction tendencies. In both taxa, initiated but early reduced bracteoles are present.
Pendulum symmetry in S. formosa is probably associated with distichous phyllotaxis. In C. arietinum, strong reduction tendencies are revealed. Based on studies of A. precatorius, the papilionoid pseudoraceme is reinterpreted as a compound raceme with condensed lateral axes. From an Abrus-like inflorescence, other types can be derived via reduction of flower number and synchronization of flower development. A plea is made for uniform usage of inflorescence terminology.
花序结构决定了花在开花期间的时空排列，因此对生殖成功至关重要。豆科是最大的被子植物科之一，其中包括一些重要的作物。在豆科蝶形花亚科中，总状花序是最常见的花序类型。然而，通过各种发育过程，已经进化出了一系列其他的花序类型。对美丽胡枝子、鹰嘴豆、鸡骨草、肾唇鸢尾和黑荆的花序进行重新研究，深入了解了简化机制，并提出了一个关于蝶形花伪总状花序进化的新假说。
使用扫描电子显微镜（SEM）研究花序形态和发育。
美丽胡枝子的花序为伞形花序，具有罕见的摆动对称类型，可能由托叶引发。鹰嘴豆花序简化为一朵花。早期形成的腹侧隆起是花序的不育顶端（即花序是开放的，而不是由花终止）。在鸡骨草的部分花序中，轴被简化，其分生组织向主花序转移。花的发生遵循一种奇特的摆动模式。肾唇鸢尾和黑荆的部分花序显示出简化的趋势。在这两个分类群中，都存在已启动但早期被简化的小苞片。
美丽胡枝子的摆动对称可能与二列互生的叶序有关。在鹰嘴豆中，表现出强烈的简化趋势。基于对鸡骨草的研究，重新解释了蝶形花伪总状花序为具密集侧轴的复合总状花序。从类似于鸡骨草的花序可以通过减少花的数量和同步花的发育来衍生出其他类型的花序。呼吁统一使用花序术语。
