蔓性刀豆，又名红凤豆、红刀豆、海刀豆、巴西豆，俗称刀板豆。是属于豆科刀豆属的一年生缠绕性草质藤本植物，植株长3-5米，会开白色或紫红色的蝶形花，为穗状花序。花期过后每个花穗结2-5豆荚，荚长25-33厘米，内含4-7颗种子。
红刀豆的嫩荚味道鲜美，营养丰富，并可作炒、腌制、制作酱菜等用途，是出口蔬菜的品种之一。

近年来，商人看中了红刀豆种子外层坚硬，发芽时生长奇特，因此在其种子表面用激光刻上“我爱你”、“生日快乐”等祝福语句后，把它改名为“魔豆”，制成易开罐装或整粒种子在观赏花卉市场出售，亦有人把种子藏在人造蛋壳内，称为“魔蛋”。除红刀豆之外，白刀豆亦是经常用来制作“魔豆”的刀豆属植物之一。白刀豆外型较红刀豆小，表皮是白色，很容易分辨。

"Sword Bean" and variants redirect here. This term is also used for other legumes, notably the Common Jack-bean.

Canavalia gladiata, usually called sword bean, is a domesticated plant species in the legume (Fabaceae) family. The legume is a used as a vegetable in interiors of central and south central India, though not commercially farmed. In Telugu it is called 'chamma kaya' also called 'Tammi kaya'. In Tamil it is called 'valavaraik-kay' or 'valavaran-gai' which means, the vegetable that looks like a sword.. The fruits are eaten as a vegetable in Africa and Asia.