Male plants

Cycads pollination by insects may be one of the earliest forms of insect-pollination. Like conifers, cycads bear their reproductive cells in cones rather than flowers. Individual cycad plants are either male or female, male plants having pollen cones and female plants, seed cones. Fertilization requires transfer of pollen grains from pollen cones to seed cones. The role of insects in this process has received attention in a cycad commonly known as the cardboard palm (Zamia furfuracea). This is a handsome horticultural plant with... 

The weevils do not linger to feed and breed in seed cones as they do in pollen cones, even though starch is plentiful here as well. This behavioral difference is not yet completely understood, but it seems that the cones of female plants contain an active poison called beta-(methylamino)alanine (BMAA). This substance is a recognized neurotoxin for mammals and is believed to affect insects as well. The male plants pollen cones also contain BMAA, but in a bound form that renders it harmless, allowing the weevils to nest and feed with impunity. In contrast, seed cones contain free toxic BMAA that presumably repels weevils and causes them to depart after quick examination and inadvertent pollination. 

Kif is planted in this high, mountainous region early in March, shortly after the spring snows have thawed. Male plants are culled when the plants are old enough for sex to be determined. It is harvested during the month of August and in early September, when the blossoms are ripe but before their plants go to seed. 

In the northern hemisphere, seeds are usually planted in April or May. Depending upon conditions—more than ten hours of light a day, for example, greatly hastens growth—maturation of the male plants takes ten to twelve weeks. For about the first month, the two sexes are indistinguishable then the males tend to get taller and the females become bushy and squat Eventually, the young female plant has at least twice the weight of the male. 

At the first breeze the entire load of pollen drops—apparently the supreme moment for the male. It begins to lose its color and waxy texture soon after, then gradually wrinkles and dries over the next few days, from the base of the plant up. Contrary to a rumor circulated for years, leaves and flowers of the male plant are psychoactive, though they diminish in potency rapidly after pollination. They should be harvested before shedding their pollen, unless the pollen is needed for seed production. 

Of the drugs that are contained in cannabis products, it is A -tetrahydrocannab-inol (A -THC) (1) which is responsible for the pharmacological activity of cannabis. This compound is formed in the glandular trichomes (see below) which are found on the surface of the plant. Cannabis sativa is dioecious, that is, it has both male plants and female plants. These are most easily recognized at the flowering stage because the flower structures are different. The female plants are preferred because they produce more of the glandular trichomes and, as a consequence, are richer in cannabinoids. 

Fig. 154.—Hair-cap moss (Polylrichum commune). A, male plant B, same, proliferating C, female plant, bearing sporogonium D, same g, gametophyte s, seta c, capsule 0, operculum a, calpytra E, top view of male plant. (Gager.),...

As they became more familiar with the plant, the Chinese discovered it was dioecious. Male plants were then clearly distinguished from females by name (hsi for the male, chu for the female). The Chinese also recognized that the male plants produced a better fiber than the female, whereas the female produced the better seeds. (Although hemp seed was a major grain crop in ancient China until the sixth century A.D., it was not as important a food grain as rice or mullet.)... 

Shen-Nung s solution to the problem was to advise that yin, the female plant, be the only sex cultivated in China since it produced much more of the medicinal principle than yang, the male plant. Marijuana containing yin was then to be given in cases involving a loss of yin from the body such as occurred in female weakness (menstrual fatigue), gout, rheumatism, malaria, beri-beri, constipation, and absentmindedness. 

As soon as the king and queen were chosen, they were saluted and hoisted onto the soldiers of their subjects so that they could make crosses on the beams of the houses. These crosses were supposed to protect the houses during the coming year against evil spirits. But the real point of the selection was auguiy it was an attempt to peer into the future to determine what the next year s hemp crop would be like. If the king were taller than the queen, then the male plant would be taller than the female (and the fiber would therefore be better). If the queen were taller, then the female hemp plants would be taller and the fiber would nor be as good. 

Cannabis is also remarkable for being able to change its sex - under certain conditions, male plants can turn into females and vice versa. Its hereditary characteristics are also transmutable - plants grown from seeds taken from American plants and grown in India will, within a few generations, resemble plants that have always grown in India more closely than their American relatives, and vice versa for seeds taken from India and grown in America. 

Cannabinoids also appear to play another important role in the plant s biological success. Scientists have found evidence that cannabinoids released into the soil help the plant compete for growing room by chemically discouraging the seeds of other species from germinating too close to a cannabis plant. The sticky nature of cannabinoid resins may also help pollen grains from male plants adhere to the flowering parts of the female plants. 

From the bark of the hemp stems, bast is obtained. The bast fibres are separated mechanically from the woody parts modern separation methods employ enzymes or steam pressure, surfactant or ultrasound processes. The best hemp fibres are obtained from the male plants being very durable. They are used for the manufacture of ropes, cords, nets, strings, yarn, carpets, textiles and sailcloth. The wood is used for the manufacture of insulating material, but it is also well suited for the production of paper, cardboard and cartons, since its lignin content amounts to only 10% (compared to 20-25% from trees). 

Gametophytic thalli of the carrageen red macroalga Chondrus cripus (Rhodophyta, Gigartinales) were obtained from CECA S.A. (Carentan, France) and cultivated in natural filtered seawater, and in a closed loop aerated assimilation chamber as previously described (3). Male plants of Chara corallina Klein were cultured in the... 

Most plants contain both male and female reproductive parts, thus simplifying pollination. Some plants, however, such as hollies, have separate male and female plants, and the female plant cannot produce red berries unless a male plant, which produces the pollen, is nearby so that pollination can take place. 

The internodes on the stem produce one pair of leaves. The palmatipartite leaves grow on leaf petioles and are divided into lancet-shape sections. The number of sections (5-11) differs, depending on the location on the stem. The closer to the top of the stem, the lower the number of sections. On the top of the male plant, the leaves consist only of a single section. In the bottom and middle part of the stem, the leaves are arranged opposite, while within the inflorescence, alternately. The leaves fade gradually and fall off the plant as the plant matures [9]. 

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