Look at this weirdo shrub. This happens sometimes. A perfectly nice green columnar top shooting up from a yellow, spreading, variegated base. Strange stuff like variegations and weeping forms are found from time to time growing on regular plants and these 'sports', mutant shoots, are kept by grafting them to regular root bases. But every now and then portions of these 'sports' revert to the more normal type. TPP has a variegated agave, and after it flowered, the main shoot began to die and in the process it produced side shoots that continue the growth of the plant. But in this case half the side shoots were totally green probably because the population of cells in a particular meristem did not have chlorophyll free cells that make the variegation. If they contain cells of both normal and cholorphyll free types, the shoots are called chimeras, part one thing, part another (see link below). If TPP has left them alone, his agave would have been a regular green plant for the future. Here, the reversion produced a green shoot without the yellowish pigmentation, or rather with it, but the yellow being masked by regular chloroplasts. A quick nip with the clippers would have left this a spreading yellowish evergreen (yellow?) shrub. But no one noticed, or they did but didn't clip the green shoot, now the more vigorous green shoot with the regular columnar growth pattern has taken over. Sometimes people inadvertently prune away variegated portions of their ornamental plants, and they wonder what happened. If the shoot becomes completely white, devoid of pigmentation, it will grow only as a "parasite" on the rest of the plant. These are best known for redwoods.