Also on display are an array of tropical fish. The Bloedel Floral Conservatory houses about 500 species and varieties of plants from deep jungle to desert clime, all within the dome. The conservatory is home to Bougainvilleas and Browallias, citrus and coffee trees, Eucalypti and epiphytes, Euphorbia and various figs, Gardenia and Hibiscus. Magnolia trees share space with delicate lilies, yucca with pteris (ferns). Located above sea level, the conservatory itself is in diameter, high, and is made up of 1,490 plexiglass bubbles and 2,324 pieces of extruded aluminum tubing. There are 32 different shapes and sizes, but each bubble measures 9 inches in height. It contains 8 air circulating units and 24 mist sprayers to control temperature and humidity for 3 separate climatic zones inside the dome. The Triodetic System was developed and patented in Canada in 1955 by F. Fentiman and Sons of Ottawa. This system was originally made from aluminum components. It uses extruded cylindrical solid aluminum hubs (nodes) with slots, and tubular aluminum or steel members with matching crimped ends. Triodetic joints resist tension, compression and combined cross loading. Triodetic domes are designed as double curved shells which allow increased structural advantages for the span:rise ratio. The use of triangles makes the structure rigid and very strong, and similar to the geodesic design, stresses are transmitted throughout the structure. Even with light structural components, triodetic domes are able to withstand extremes of wind and even earth quakes. This enables a large interior volume to be enclosed without the need for internal supporting columns. In the plaza adjacent to the conservatory dome is a bronze sculpture by Henry Moore, "Knife Edge Two Piece 1962–65". It was donated to the Park Board by avid modern art collector Prentice Bloedel and his wife Virginia along with the funding to build the conservatory, the surrounding plaza and fountains. Moore created this piece in 1962, and authorized three castings of the work. The first stands on Nelson Rockefeller's New York estate, the second is outside the House of Lords, in London, England, and the third is situated to the south of the conservatory next to the Dancing Fountains. Knife Edge was the first non-commemorative sculpture accepted by the Vancouver Park Board. It was donated by Prentice Bloedel and his wife Virginia to tie the conservatory dome and the design of the adjacent fountain plaza to the inspiration and power of nature.