Claw Cactus (Schlumbergera)

Claw Cactus (Schlumbergera)

There are only three recognized species of schlumbergera, and specimens grown as house plants are more likely to be hybrids than repre­sentatives of the true species. In the wild these jungle cacti inhabit moist tropical forests, where they grow in pockets of leaf debris in the clefts of tree branches, and they do best if indoor conditions approximate those of their natural habitat. A good aver­age specimen is likely to have a height and spread of about 12 inches. The densely branching, mainly pendent stems consist of many thin, flat, medium green segments. Each of these joined segments is 1- 1 ½ inches long and  ¾ - 1inch wide and has a prominent midrib. The precise shapes and other features of the segments vary considerably among the species and hybrids. Minuscule areoles, some of which bear tiny bristles, are situated in notches along the edges of the segments. There is a bigger, elongated areole at the tip of the end segment of each stem, and flowers arise in abun­dance from these terminal areoles. Each areole can produce a single bloom or a pair, and there is a re­latively long flowering period some­time in early or late winter.

The appearance of flowers during the Christmas season in some of the hybrids has given rise to the name Christmas cactus, loosely applied to several forms. The flowers are unusual for cacti, since they are not symmetri­cal in shape but have different right and left halves (as do snapdragons or pea flowers). Each bloom is about i inch across and 1 ½  -3 inches long, and the longer flowers may seem to consist of separate tiers of petals. Individual blooms last for a few days, and a specimen with many buds may flower for several weeks.

RECOMMENDED SCHLUMBERGERAS

S. 'Bridgesii' (also called S. 'Buck-leyi'; popularly known as Christmas cactus) is a hybrid between S. truncata and the rarely seen species 5. russel-liana. The stem segments have rounded notches and rounded ends.

The flowers are magenta and appear around Christmas or somewhat later. S.   truncata   (also  called Zygoccm truncatus; commonly known as claw, crab,   or   Thanksgiving cactus) has I stem segments with deeply incised notches along the edges and pronglike projections, not unlike a crab's claws, I at the ends. The pink to deep red flowers have attractively turned-back I petals and usually begin to appear a few weeks before Christmas. S. trun­cata is a parent of most of the schlum-bergera hybrids. There are many of J these, and they are sold under a variety of names that are apt to differ in different  places  at  different times.  Some have rounded stem segments, others have the more pointed type (and these latter are often informally called crab cacti). The flowers also differ   considerably   in   shape, and! flower color may be white or almost any shade of pink or red.

In addition to hybridizing these plants, professional growers have produced a novelty form of the Christmas cactus which can occasionally be obtained. A schlumbergera is grafted onto the top of a tall, single-stemmed cactus, and as the schlumbergera grows, its many stems arch over to form a "weeping" plant. In a large specimen the graft is com­pletely hidden and when the plant is in full flower, the effect is impressive.

PROPER CARE

Light Like other jungle cacti, schlum-bergeras should never be exposed to full summer sunlight. Medium light at a partly shaded window is best throughout spring, summer, and fall. The less powerful winter sun is not so likely to harm these plants. Flower buds start to form in early fall, and full flowering is initiated by the restricted light of shortening days. Once these cacti have begun to bud, do not keep them in a living room where artificial lights may be burning virtually all evening every day. To encourage the abundant flowering characteristic of healthy schlumbergeras, either move plants to rooms  generally  left  un-lighted after dark or cover budding plants with black plastic sheets when lights are switched on. If a specimen that should flower in late December I  docs not usually flower till well after  Christmas, try helping it by giving it  an extensive period of artificial short    days: Beginning in early fall, put the  plant in a dark place every day at    twilight, and keep it there till morning. This must be done very carefully  .

Temperature Normal room tem­peratures are suitable throughout the year. All schlumbergeras will benefit from being placed in a shady spot   outdoors during late spring and sum- mer, but move them back indoors before the start of cold weather.

Watering Although these are gen­erally winter-flowering plants, their stems grow most actively during the months from early spring to early fall. During the entire year except for a brief period following the end of the flowering period, water plentifully as often as necessary to keep the potting mixture thoroughly moist, but do not allow pots to stand in water. When flowering  ceases   (probably  in  late winter), reduce amounts, and water only moderately—enough to moisten the mixture  at   each  watering  but allowing the top half-inch of the mix­ture to dry out before watering again. Resume plentiful waterings as soon as new stem growth starts in spring. For increased   humidity   mist-spray   the plants daily, especially in spring and summer. Because schlumbergeras dis­like hard water (water with a high calcium  content),   use  rainwater,   if possible,  for  all watering purposes. Never permit the potting mixture to dry out completely.

Feeding Except during the brief per­iod   of   moderate    watering    im­mediately following the end of the flowering   period,    apply   a   high-potassium, tomato-type fertilizer once every two weeks throughout the year.

Potting  and  repotting  Although actively growing schlumbergeras re­quire plentiful watering, they must not be permitted to get waterlogged. To avoid this possibility, use a peat-based potting  mixture  made  more porous by the addition of one part of coarse sand or perlite to every three parts of the standard mixture. Grow plants in ordinary pots or hanging baskets. The latter are particularly suitable for larger specimens; to retain the potting mixture in the baskets, line them with sphagnum moss.

Repot every year when plants have finished flowering. Move each plant into a container one size larger only if roots have filled the current one. Otherwise, shake off the spent potting mixture, replace the plant in its con­tainer, which has been cleaned, and add fresh mixture as necessary. Schlumbergeras do not have large root systems, and a specimen a foot across can be grown in a 4- or 5-inch pot or basket.

Propagation Schlumbergeras are easy to propagate from cuttings at any time in the spring or summer. Re­move a section of stem consisting of two or three joined segments, allow it to dry for a few hours, and push the bottom segment gently into a 3-inch pot of the potting mixture recom­mended above. Insert the segment just deep enough to support the whole cutting. Several such cuttings may be inserted around the edge of a larger container, if desired. Treat the cuttings as mature plants. They should start into growth within four weeks.

Seed is sometimes available, usually of "mixed hybrids." Raising these cacti from seed presents no problems, but it will be three or four years before the resultant plants can be evaluated.

Special points Although it is com­mon to see schlumbergeras covered with buds or in full bloom in florists' shops at Christmastime, do not be disappointed if plants grown in the home fail to flower by the calendar. They will usually bloom later. Pro­fessional nurserymen have perfected the art of forcing these plants for the Christmas market.

Some growers find that flower buds drop off after they have formed. This can result from such obvious causes as drafts, sudden changes of temperature, or either dried-out or waterlogged roots. There is another possibility, however: If these plants are turned around when buds are small, the buds themselves are likely to try to turn to face the light, and the effort will weaken them. So when moving a budding schlumbergera, be careful not to change the plant's pos­ition relative to the source of light.

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