In biology, there is such a thing - simulating forms. This is not the first time that the everyday and scientific meanings of the word do not match. "Simulating" in biology does not mean "depicting an ailment". Simulating forms are simply superficially similar animals or plants that are not really related. Many other names have been introduced for this similarity: homoplasia, convergence, parallelism, homeomorphy, mimicry, etc. But these are terminological jungles that it is better not to get into yet.

In biology, there is such a thing - simulating forms. This is not the first time that the everyday and scientific meanings of the word do not match

Probably, many novice mushroom pickers with annoyance threw aside the valu, which from a distance looks like a porcini mushroom. If such a mushroom does not get into the pan, this ends the conflict with the simulating form. It is enough to look under the mushroom cap, and the simulation is exposed. But paleobotanists are not always so easy to look under the hat. The plant almost never falls into his hands entirely. Usually these are either only stems, or only leaves, seeds, cones, roots, etc., and they can be very similar in a variety of plants (recall the nettle and stinging nettle, which belong to different families). But sometimes it happens the other way around: at first glance, you would never recognize close relatives. An inhabitant of the middle band in the sheet in fig. 1 does not recognize an oak, meanwhile it is an oak, and its acorns are depicted next to it to confirm. For a specialist in modern plants, such anomalies are not a problem. He sees the whole plant, "with acorns". A paleobotanist who studies prints that might include such oaks will also see the catch if he knows modern plants. But, as soon as he begins to descend into the depths of geological epochs, he cannot do without knowledge of modern plants alone. The paleobotanist must look for some important marks on the fossil leaves themselves that distinguish or, conversely, unite plants into natural systematic categories.

It is no coincidence that the word "important" is inserted here. Similarity and difference are loose concepts. All leaves are somewhat similar, and at the same time, no two are the same. Speaking here about the differences in leaves, we mean that they belong to different systematic categories. Two leaves of the same species have intraspecific differences, two leaves of different species have species differences. Next come the generic, family differences (from the systematic group "family"), and so on up to the type. All these categories - species, genus, family, etc. - are established in botany for the plant as a whole, everything is taken into account, but the main attention is on the reproductive organs. They are the least subject to random changes and therefore the most reliable for taxonomy. This is where the main troubles of the paleobotanist begin, to which plants come “disassembled”, with broken and completely lost parts. How to evaluate the observed differences and similarities, what to give preference to?