and growth Lilies can be propagated in several ways; by division of the bulbs by growing-on bulbils which are adventitious bulbs formed on the stem by scaling, for which whole scales are detached from the bulb and planted to form a new bulb by seed; there are many seed germination patterns, which can be complex by micropropagation techniques (which include tissue culture); commercial quantities of lilies are often propagated in vitro and then planted out to grow into plants large enough to sell. A highly efficient technique for multiple shoot and propagule formation was given by Yadav et al., in 2013. Plant grow regulators(PGRs) are used to limit the height of lilies, especial those sold as potted plants; commonly used chemicals include ancymidol, fluprimidol, paclobutrazol, and uni-conazole, which are applied to the foliage and retard the biosynthesis of gibberellins, a class of plant hormones responsible for stem growth. Toxicity Some Lilium species are toxic to cats. This is known to be so especially for Lilium longiflorum, though other Lilium and the unrelated Hemerocallis can also cause the same symptoms. The true mechanism of toxicity is undetermined, but it involves damage to the renal tubular epithelium (composing the substance of the kidney and secreting, collecting, and conducting urine), which can cause acute kidney failure. Veterinary help should be sought, as a matter of urgency, for any cat that is suspected of eating any part of a lily – including licking pollen that may have brushed onto its coat. Culinary uses Chinese cuisine Lily bulbs are starchy and edible as root vegetables, though bulbs of some species may be too bitter to eat. Lilium brownii var. viridulum, known as 百合 (pak hop; ), is one of the most prominent edible lilies in China. Its bulbs are large in size and not bitter. They were even exported and sold in the San Francisco Chinatown in the 19th century, available both fresh and dry. A landrace called 龍牙百合 () mainly cultivated in Hunan and Jiangxi is especially renowned for its good-quality bulbs. L. lancifolium () is widely cultivated in China, especially in Yixing, Huzhou and Longshan. Its bulbs are slightly bitter. L. davidii var. unicolor () is mainly cultivated in Lanzhou and its bulbs are valued for sweetness. Other edible Chinese lilies include L. brownii var. brownii, L. davidii var. davidii, L. concolor, L. pensylvanicum, L. distichum, L. martagon var. pilosiusculum, L. pumilum, L.