Ted Lart of Silver Spring, has submitted the following information in answer to a question about grafted cactus:

"Certain cactus nurseries are marketing grafted cactus under the names 'Moon Cactus' or 'Oriental Cactus.' These are no different from any other grafted cactus, other than the name. Those with a green cactus grafted on top can be rooted in the manner described in the Indoor Gardener column. Those with the more exotic colors on top (rose, pink, orange, yellow etc.) cannot. These are mutations which have no chlorophyl and cannot survive unless grafted on top of a green (chlorophyl-producing) cactus."

Mrs. David Eden. Bethesda, requests guidance on bringing houseplants back into the house after a summer outdoors. She asks also whether she can bring her hanging basket of Impatiens in to hang in her kitchen, and requests a suggestion on what to use around a Norfolk Island Pine that has lost lower branches.

A. A hanging basket of Impatiens can be brought indoors if you have a sunny place in front of a brightly lighted window. Flowering plants need high light intensity to bloom indoors. Fluorescent lights for 14 to 16 hours per day can substitute for sunlight. In either case, the plant may deteriorate upon being brought indoors because of the sudden change of light and reducation of humidity. A better practice is to take cuttings of Impatiens and carry small plants through the winter, providing good light to induce good green growth and bloom.

Boston Fern will make an effective filler in the container with Norfolk Island Pine.

Suggestions for bringing plants indoors after a summer in the garden or on the patio were given in the Indoor Gardener column on Sept. 29.

Dr. Henry Hopp. Bethesda, has requested names of sources of Sansevieria Hahni, Peperomia Obtusifolia and Peperomia "Watermelon."

A. Sansevieria Hahni is available at The Plant Pavilion, 3015 M St. NW, Washington; Silver Hahni and Golden Hahni are also sometimes available. The Plant Pavilion tries to keep a good stock of a number of Peperomias, including Watermelon.

Potomac Garden Center, Potomac, Md., has Sanservieria Hahni.

American Plant Food Co., River Road, Bethesda, has Peperomia Obtusifolia.

Dr. Sally MacDonald, Silver Spring, writes: "My jade plant has a scale - any suggestions? I will wash it with Ivory soap and water."

A. Pick off the scales with a sharp fingernail or with the tip of a nail file. The soapy water bath will further help to cleanse the plant.

If you have recently bought a dracaena, a philodendron, a Chinese evergreen, or some other favorite foliage plant, chances are that it came from Florida. According to the crop reporting service of the U.S. Department of Agriculture, most of the foliage plants grown in America originate in Florida, and in wholesale sales Florida ranks way ahead of California and Texas, two other leaders in production of green plants.

During the busy months of February, March and April more than a million plants leave Florida daily, mostly by truck, some by air. The indoor foliage plantsmen grow more than 450 different species of plants. Commercial growers in the vicinity of Apopka, Fla., devote most of their energy to small plants, such as philodendron, dracaena and schefflera. South Florida nurseries grow mostly larger plants like palms, Ficus and cane varieties.

A houseplant laboratory was established near Apopka in 1969. It is the only one in the world exclusively researching tropical foliage. Such work as soil composition, shade factors necessary to make plants thrive under home conditions, interactions between light intensities, developments in watering and fertilizers, and disease and pest control studies are a continuing program.

This research when applied to production of plants in specialized nurseries, makes it possible for the indoor gardener to obtain better plants in greater variety. The U.S. Department of Agriculture estimates that the average American household now has eight to 10 plants. Some of the most confirmed indoor gardeners probably exceed this average.

According to the 1976 edition of the Guiness Book of World Records, the largest flower is that of the Mottled Orange-Brown and White Parasitic Stinking Corpse Lily (Rafflesia Arnoldia). The flower is three feet in diameter, weighs 15 pounds and the petals are 3/4 of an inch thick. As described in Hortus III and in Graf's Exotic Plant Manual, Rafflesia Arnoldia is a parasitic plant with no true leaves of its own; its primitive root system attaches itself to a specific grape-like vine for sustenance. It is native to Sumatra. Some species of Rafflesia can be grown as pot plants but not this one, and they all smell bad.

Propagation of ornamental plants from small clusters of cells in test tubes is being used by a number of nurserymen and flower growers in the United States. In the production of ferns, for example, one small runner tip can produce 2,000 to 3,000 plants and saleable four-inch plants can be grown in eight to nine months. With conventional propagation techniques, 12 to 15 months may be required. Researchers refer to this technique as meristem or tissue culture. It is an extremely complicated technique performed under rigidly controlled conditions. Presently there are 20 commercial laboratories in California producing plants by this method. Some of the plants you have been buying, especially orchids and ferns, may have been propagated in this way.