Laticifer occurrence and structure are poorly known in Sapindaceae. Occurrence is likely underestimated owing to the low production of latex in most species. We investigated 67 species from 23 genera of Sapindaceae to verify laticifer occurrence and their structural, developmental and chemical features, as well as their evolutionary history in the family. Shoots were collected from herbarium and fresh specimens for histological analyses. Three characters derived from laticifer features were coded and their ancestral states reconstructed through Bayesian stochastic mapping and maximum likelihood estimation. Only articulated non-anastomosing laticifers were found in Sapindaceae. Laticifers differentiate early during shoot development and are found in the cortex, phloem, and pith. Latex is mostly composed of lipids. Callose and suberin were detected in laticifer cell walls in some genera. Reconstruction of laticifer ancestral states showed that laticifers are present in most clades of Sapindaceae with some reversals. Callose in the laticifer cell wall was found exclusively in Serjania and Paullinia (tribe Paullinieae), a character regarded as independently derived. Occurrence of laticifers in Sapindaceae is broader than previously reported. Articulated non-anastomosing laticifers had five independent origins in Sapindaceae with some secondary losses, occurring in five out of six genera of Paullinieae and 10 other genera outside Paullinieae. Particularly, callose in the laticifer cell wall evolved independently twice in the family, and its occurrence may be interpreted as a key-innovation that promoted the diversification of Paullinia and Serjania. Our study suggests that laticifer characters may be useful in understanding the generic relationships within the family.

无患子科中乳管的发生和结构知之甚少。由于大多数物种的乳胶产量较低，其发生率可能被低估。我们调查了无患子科 23 属 67 种，以验证乳管的出现及其结构、发育和化学特征，以及它们在科中的进化历史。从植物标本室收集芽和新鲜标本进行组织学分析。对源自乳管特征的三个性状进行了编码，并通过贝叶斯随机映射和最大似然估计重建了它们的祖先状态。在无患子科中只发现了铰接的非吻合乳管。乳管在芽发育早期分化，存在于皮层、韧皮​​部和髓中。乳胶主要由脂质组成。在一些属的乳管细胞壁中检测到胼胝质和木栓质。乳管祖先状态的重建表明，乳管存在于无患子科的大多数进化枝中，但有一些逆转。乳管细胞壁中的胼胝质仅存在于塞贾尼亚和泡莲属（Paullinieae 部落），一个被视为独立衍生的字符。无患子科中乳管的出现范围比以前报道的要广泛。铰接式非吻合乳管在无患子科中有五个独立起源，但有一些次生损失，发生在泡桐科 6 个属中的 5 个属和泡泡科以外的其他 10 个属中。特别是，乳管细胞壁中的胼胝质在该家族中独立进化了两次，它的出现可能被解释为促进乳管多样化的关键创新。泡莲属和塞贾尼亚。我们的研究表明，乳管特征可能有助于理解家庭内的一般关系。