<P> Olive trees show a marked preference for calcareous soils, flourishing best on limestone slopes and crags, and coastal climate conditions . They grow in any light soil, even on clay if well drained, but in rich soils, they are predisposed to disease and produce poorer oil than in poorer soil . (This was noted by Pliny the Elder .) Olives like hot weather and sunny positions without any shade, while temperatures below − 10 ° C (14 ° F) may injure even a mature tree . They tolerate drought well, due to their sturdy and extensive root systems . Olive trees can live for several centuries and can remain productive for as long if they are pruned correctly and regularly . </P> <P> Only a handful of olive varieties can be used to cross-pollinate .' Pendolino' olive trees are partially self - fertile, but pollenizers are needed for a large fruit crop . Other compatible olive tree pollenizers include' Leccino' and' Maurino' .' Pendolino' olive trees are used extensively as pollenizers in large olive tree groves . </P> <P> Olives are propagated by various methods . The preferred ways are cuttings and layers; the tree roots easily in favourable soil and throws up suckers from the stump when cut down . However, yields from trees grown from suckers or seeds are poor; they must be budded or grafted onto other specimens to do well . Branches of various thickness cut into lengths around 1 m (3.3 ft) planted deeply in manured ground soon vegetate . Shorter pieces are sometimes laid horizontally in shallow trenches and, when covered with a few centimetres of soil, rapidly throw up sucker - like shoots . In Greece, grafting the cultivated tree on the wild tree is a common practice . In Italy, embryonic buds, which form small swellings on the stems, are carefully excised and planted under the soil surface, where they soon form a vigorous shoot . </P> <P> The olive is also sometimes grown from seed . To facilitate germination, the oily pericarp is first softened by slight rotting, or soaked in hot water or in an alkaline solution . </P>

What is the pit of an olive called