Lipids are a broad group, affording various forms of energy storage, though with other important biological roles as well. Fats, waxes, sterols (e.g., cholesterol), and fat-soluble vitamins (A, D, E, K) are exemplary lipids.
Lipids are used to make cell membranes, of both plants and animals. Lipids also play a vital role of cell signaling.
In a process termed lipogenesis, an oversupply of carbohydrate are converted to triglycerides for energy storage. Conversely, these fatty acids are broken down for energy via beta oxidation: a similar, though not identical, reversal of lipogenesis.
Plants stuff their seeds with carbs, lipids, and proteins before sending them on their way to make a life for themselves. They also pack in a beneficial microbiome, to make sure a seedling starts out among friends.
For those that don’t make it to sprouting, seeds provide a rich nutrient source for animals.