an extreme example of this, winter annuals sprout in the fall, grow through the winter, and flower and die in the spring. Just like with trees, shade tolerance in herbaceous plants is diverse. Some early-leafing out plants will persist after the canopy leafs out, whereas others rapidly die back. In many species, whether or not this happens depends on the environment, such as water supply and sunlight levels. Hydrangea hirta is a shade-tolerant deciduous shrub found in Japan. Although most plants grow towards light, many tropical vines, such as Monstera deliciosa and a number of other members of the family Araceae, such as members of the genus Philodendron, initially grow away from light; this is a dramatic example of sciophilous growth, which helps them locate a tree trunk, which they then climb to regions of brighter light. The upper shoots and leaves of such a Philodendron grow as typical light-loving, photophilic plants once they break out into full sunshine. Trees In forests where rainfall is plentiful and water is not the limiting factor to growth, shade tolerance is one of the most important factors characterizing tree species. However, different species of trees exhibit different adaptations to shade. The eastern hemlock, considered the most shade-tolerant of all North American tree species, is able to germinate, persist, and even grow under a completely closed canopy. Hemlocks also exhibit the ability to transfer energy to nearby trees through their root system. In contrast, the Sugar Maple, also considered to be highly shade-tolerant, will germinate under a closed canopy and persist as an understory species, but only grows to full size when a gap is generated. Shade-intolerant species such as willow and aspen cannot sprout under a closed canopy. Shade-intolerant species often grow in wetlands, along waterways, or in disturbed areas, where there is adequate access to direct sunlight. In addition to being able to compete in conditions of low light intensity, shade-bearing species, especially trees, are able to withstand relatively low daytime temperatures compared with the open, and above all high root competition especially with subordinate vegetation. It is very difficult to separate the relative importance of light and below ground competition, and in practical terms they are inextricably linked. See also Daily Light Integral List of tree species by shade tolerance PI curve References Plant physiology Forest ecology