ornately carved wooden stands. Often, rocks, miniature ceramic structures (like buildings and bridges), and figurines are added to give the proper scales as part of the natural scenery. These miniatures add to the symbolism of a penjing specimen, by providing a social or historical context in which to interpret the overall penjing design. These miniature landscapes include trees which are frequently over a hundred years old. Like the plants in the Chinese garden, they have been carefully selected and tended so that they develop into twisted and gnarled shapes reminiscent of their full-size counterparts in the wild. Like Chinese gardens, these miniature landscapes are designed to convey landscapes experienced from various viewpoints - a close-up view, a medium-range view or a panorama. As an art form, penjing is an extension of the garden, since it enables an artist to recreate parts of the natural landscape in miniature. Penjing is often used indoors as part of a garden's overall design, since it reiterates the landscape features found outside. Penjing pots grace pavilions, private studies or living rooms, and public buildings. They are either free-standing elements within the gardens or are placed on furniture such as a table or bookshelf. Sometimes a lattice display stand is built which adds particular prominence to the penjing specimen and exemplifies the interplay between architecture and nature. Penjing seeks to capture the essence and spirit of nature through contrasts. Philosophically, it is influenced by the principles of Taoism, specifically the concept of Yin and Yang: the idea of the universe as governed by two primal forces, opposing but complementary. Some of the contrasting concepts used in penjing include portrayal of "dominance and subordination, emptiness (void) and substance, denseness and sparseness, highness and lowness, largeness and smallness, life and death, dynamics and statics, roughness and meticulousness, firmness and gentleness, lightness and darkness, straightness and curviness, verticality and horizontality[,] and lightness and heaviness." Design inspiration is not limited to observation or representation of nature, but is also influenced by Chinese poetry, calligraphy, and other visual arts. Common penjing designs include evocation of dragons and the strokes of well-omened characters. At its highest level, the artistic value of penjing is on par with that of poetry, calligraphy, brush painting and garden art. Styles Styles of the traditional Penjing in China are mainly classified by the most representative (dominant) plants used, and named after the regions of their origin. Since