Maturation: The maturation of Cannabis is normally annual and its timing is influenced by the age of the plant, changes in photoperiod, and other environmental conditions. When a plant reaches an adequate age for flowering (about two months) and the nights lengthen following the summer solstice (June 21-22), flowering begins. This is the triggering of the reproductive phase of the life cycle which is followed by senescence and eventual death. The leaves of Cannabis plants form fewer leaflets during flowering until the floral clusters are formed of trileaflet and mono-leaflet leaves. This is a reversal of the heteroblastic (variously shaped) trend of increased leaflet number through the pre-floral stage. The staminate and pistillate sexes of the same strain mature at different rates. Staminate plants are usually the first to begin flowering and releasing pollen. In fact, much pollen is released when the pistillate plants show only a few pairs of primordial flowers. It would seem more effective for the staminate plant to release pollen when the pistillate plants are in heavy flower to ensure good seed production. Upon deeper investigation, however, it becomes obvious that early pollination is advantageous to survival. Pollinations that take place early form seeds that ripen in the warm days of summer when the pistillate plant is healthy and there is less chance of frost damage or predation by herbivores. If conditions are favorable, the staminate plant will continue to produce pollen for some time and will also fertilize many new pistillate flowers as they appear. After a month or more of shedding pollen the staminate plants enter senescence. This period is marked by the yellowing and dropping of the foliage leaves, followed by diminished flower and pollen production. Eventually, all the leaves drop, and the spent, lifeless stamens hang in the breeze until fungi and bacteria return them to the soil. Pistillate plants continue to develop up to three months longer as they mature seeds. As the calyxes of the first flowers to be pollinated dry out, each releases a single seed which falls to the ground. Since new pistillate flowers are continually produced and fertilized, there are nearly always seeds ranging in maturity from freshly fertilized ovules to large, dark, mature seeds. In this way the plant is able to take advantage of favorable conditions throughout several months. The effectiveness of this type of reproduction is demonstrated by the spread of escaped Cannabis strains in the midwestern United States. In these areas Can nabis abounds and multiplies each year, through the timely dehiscence of millions of pollen grains and the fertilization of thousands of pistillate flowers, resulting in thousands of viable seeds from each pistillate plant. As the pistillate plant senesces, the leaves turn yellow and drop, along with the remaining mature seeds. The rest of the plant eventually dies and decomposes. Although the staminate plants begin to release pollen before the pistillate plant has begun to form floral clusters, pistillate plants actually differentiate sexually and form a few viable flowers long before most of the staminate plants begin to release pollen. This ensures that the first pollen released has a chance to fertilize at least a few flowers and produce seeds. The production of prominent pistils makes pistillate plants the first to be recognizable in a crop, so early selection of seed-parents is quite easy. Often the primordia of staminate plants first appear as vegetative growth at the nodes along the main stalk and do not differentiate flowers for several weeks. Pistillate plants also may develop vegetative growth in place of the usual primordial calyxes and this growth makes staminate plants indistinguishable from pistillate plants for some time. This is often frustrating to sinsemilla Cannabis cultivators, since the staminate plants that are hesitant to differentiate sex take up valuable space that could be utilized by pistillate plants. Also, juvenile pistillate plants are occasionally mistaken for staminate plants if they are slow to form calyxes, since vegetative growth at the nodes could appear to be staminate primordia. robert clarke - marijuana botany
