A woody plant of a certain size is called a shrub when, unlike trees, it does not stand on a single trunk or stem, but branches from the same base. The bushes can be several meters high. The biome or ecosystem with a predominance of shrubs is called scrub. Not all woody plants branched from the base should be called shrubs; for example, thyme (Thymus) or lavender (Lavandula) are woody shrubs or, as it is also said, sub-bushes. Terms such as tree, bush or bush describe biotypes in the common language and are more or less equivalent to other technical ones; the botanical equivalents for this concept extend between the terms cameophyte, nanofanerófito and microfanerófito. It is common for species that are normally presented as shrubs to grow as trees, or where ecological circumstances are different, such as the kermes oak (Quercus coccifera) in North Africa, or by deliberate effort in cultivation, as seen in times with oleander (Nerium oleander). The shrubs or sufrútices develop secondary tissues, but only in the region near the base, keeping the upper part of the plant always with young tissues.