Aldrovanda vesiculosa (Droseraceae) is a rare aquatic carnivorous plant, distributed in Europe, Asia, Africa, and Australia. Aldrovanda populations can flower prolifically under favourable conditions, but seed set is very limited. We studied the structure of Aldrovanda pollen collected from flowers in different developmental stages (opened and non-opened anthers) from both European and Australian populations to elucidate pollination traits and the basis of poor seed set on the basis of microscopic observation of pollen and anther structure. Microscopic analyses of Aldrovanda pollen showed that this plant has pollen arranged in tetrads like other species in the Droseraceae family. In hydrated pollen, cytoplasmic protrusions originate from pores located along the equatorial wall of monads, and can develop into pollen tubes. Interestingly, pollen development from microspores occurs in open anthers, suggesting a delay of the developmental stages. In addition, pollen development displays altered sperm cell formation and precocious pollen germination. Precocious germination may characterize recalcitrant pollen, which naturally do not undergo dehydration before anthesis and remain partially hydrated, particularly in aquatic and wetland plants. These alterations of male gametophyte development could affect fertilization processes, and be the reason for the low reproductive capability of Aldrovanda observed both in the field and in cultures. Generally, reduced pollen longevity and very quick germination are considered an adaptation to aquatic or wet environments.

中文翻译：

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水生食肉植物 Aldrovanda vesiculosa (Droseraceae) 在雄配子体中表现出改变的发育阶段

Aldrovanda vesiculosa (Droseraceae) 是一种罕见的水生食肉植物，分布于欧洲、亚洲、非洲和澳大利亚。Aldrovanda 种群可以在有利条件下大量开花，但结实率非常有限。我们研究了从欧洲和澳大利亚种群不同发育阶段（开放和未开放的花药）的花朵中收集的 Aldrovanda 花粉的结构，以在对花粉和花药结构的显微镜观察的基础上阐明授粉性状和结实不良的基础. 对 Aldrovanda 花粉的显微分析表明，这种植物的花粉与茅膏菜科的其他物种一样呈四分体排列。在水合花粉中，细胞质突起起源于位于单子赤道壁上的孔，并可发育成花粉管。有趣的是，小孢子的花粉发育发生在开放的花药中，表明发育阶段的延迟。此外，花粉发育显示出改变的精子细胞形成和早熟的花粉萌发。早熟可能是顽固花粉的特征，花粉在开花前自然不会脱水并保持部分水合，特别是在水生和湿地植物中。这些雄配子体发育的改变可能会影响受精过程，这也是在田间和培养中观察到的 Aldrovanda 繁殖能力低的原因。通常，花粉寿命缩短和发芽非常快被认为是对水生或潮湿环境的适应。花粉发育表现出改变的精子细胞形成和早熟的花粉萌发。早熟可能是顽固花粉的特征，花粉在开花前自然不会脱水并保持部分水合，特别是在水生和湿地植物中。这些雄配子体发育的改变可能会影响受精过程，这也是在田间和培养中观察到的 Aldrovanda 繁殖能力低下的原因。通常，花粉寿命缩短和发芽非常快被认为是对水生或潮湿环境的适应。花粉发育表现出改变的精子细胞形成和早熟的花粉萌发。早熟可能是顽固花粉的特征，花粉在开花前自然不会脱水并保持部分水合，特别是在水生和湿地植物中。这些雄配子体发育的改变可能会影响受精过程，这也是在田间和培养中观察到的 Aldrovanda 繁殖能力低的原因。通常，花粉寿命缩短和发芽非常快被认为是对水生或潮湿环境的适应。尤其是水生植物和湿地植物。这些雄配子体发育的改变可能会影响受精过程，这也是在田间和培养中观察到的 Aldrovanda 繁殖能力低的原因。通常，花粉寿命缩短和发芽非常快被认为是对水生或潮湿环境的适应。尤其是水生植物和湿地植物。这些雄配子体发育的改变可能会影响受精过程，这也是在田间和培养中观察到的 Aldrovanda 繁殖能力低的原因。通常，花粉寿命缩短和发芽非常快被认为是对水生或潮湿环境的适应。