Usually a green, sour fruit is just a fruit that’s not ripe yet. If you left a lime on the tree longer would it eventually change color and become sweet, like an orange? Actually, limes do become much more yellow and less sour as they ripen. Under ripe limes are darker green and quite bitter. There are other clues to their ripeness too. Ripe limes are heavy with juice and more aromatic, with a fragrant limey smell. Most fruits we eat use similar cues to advertise ripeness.But why? Why would plants want parts of them to be eaten? Fruiting plants have evolved a partnership with certain animals in order to increase the success of their seeds. Tasty fruit pulp is the reward plants offer to animals in exchange for dispersing their seeds.

通常，一个绿色、酸味的水果还没成熟。如果你将酸橙留在树上，它最终会改变颜色，口味变甜吗？就像桔子那样吗？其实，酸橙成熟时确实变得更加黄，味道也不那么酸了。未成熟时，颜色变得深绿，味道也更苦。成熟也可其他方面看出来，成熟的酸橙果汁饱满，气味更芳香味。大部分我们吃的水果使用类似的方面来鉴定成熟度。d但是为什么？植物为什么会希望其中自身的一部分被吃掉？结果的植物进已经进化成与某些动物的关系来增加其种子的存活率。可口的水果是奖励动物们散播种子的回报。