In This Issue:

Mealybug: The Number One Enemy of Cactus, by David L. Eppele, from On The Desert

Monvillea, by Leo Martin, Plant of the Month from the St.Louis Newsletter

Notocactus and Its Allies, by Leo Martin, Plant of the Month from the St.Louis Newsletter

How are plants named? Part One: Why two names? by Leo Martin, from the St.Louis Newsletter

How are plants named? Part two: What are the naming rules, and where did they come from? by Leo Martin, from the St.Louis Newsletter


.... On The Desert By David L. Eppele (AKA El Jefe)

Mealybug: The Number One Enemy of Cactus

One of the more common of the scale insects that attack Cactus and other ornamental plants is mealybug. There are about 275 species of mealybugs known to occur in the continental United States. Mealybugs are prevalent pests in greenhouses and interior landscapes such as shopping malls, conservatories, hotels and office buildings. Mealybugs cost growers and retailers millions of dollars per year in control costs and crop damage or loss. Damage is caused by mealybugs feeding on host tissues and injecting toxins or plant pathogens into host plants. In addition, mealybugs secrete a waste product which is a syrupy, sugary liquid that falls on the leaves of the plants, coating them with a shiny sticky film. This coating serves as a medium for the growth of sooty mold fungus that reduces the plant's photosynthetic abilities and ruins the plant's appearance. Feeding by mealybugs can cause premature leaf drop, die back and may even kill the plant if left unchecked.

Mealybugs are one of the more active groups of scale insects. They have well-developed legs and remain mobile throughout their life. But once they find a suitable feeding site they move very little. Mealybugs are small insects (average 2mm long) and the body is usually covered with a white cottony or mealy wax secretion. This makes them appear like small spots of cotton on a plant. They generally have an oval body outline. The life history of mealybugs varies depending on the species. Basically, female mealybugs go through four developmental stages, called instars. As adults, the females may lay up to 600 eggs, usually in a cottony ovisac beneath her body. The eggs hatch in 6 to 14 days and the first instars or "crawlers" disperse to suitable feeding sites on new plant parts or hosts. They can survive only about a day without feeding and once they insert their stylets in a plant to feed, they generally remain anchored permanently. The crawler stage is the most fragile and easily controlled stage in the life of a mealybug. Some mealybugs do not lay eggs, but bear their young as active crawlers. Male mealybugs go through five instars and feed only in the first two instars. They die after two days, existing solely to fertilize the females.

Outdoors, most mealybugs go through one or two synchronized generations and overwinter as second instars. Indoors, especially in a greenhouse, there can be a continuous overlapping of generations and all stages can be found on a host plant at any time. I once counted 8 generations of mealybugs on a single pad of prickly pear cactus. The best way to control mealybug? Wash the plants with a 50-50 mixture of rubbing alcohol and water. Use a fairly stiff paintbrush to apply the booze. Someone once said this works better if you first cover the plant with sand. Then apply the alcohol and water and the mealybugs get drunk and kill each other by throwing rocks. I have tried this method and I can flatly state that the mealybugs do not get drunk when drenched with the alcohol and water mixture. They get dead.

One of the best methods of control of mealybugs is to purchase plants that are not infested with mealybugs. The little bugs can hide in the root system of a plant purchased in a store. Whenever I introduce new plants to our garden, I first take the plant out of the pot and remove all of the soil Then wash the roots of the plant in half-alcohol, half-water and repot it in your own soil mix. Many commercial growers discard plants infested with mealybug. They figure it is easier to grow a new plant than to try and rescue them. There are some really strong insecticides that can be used to kill mealybug, but alcohol and water is easier and safer.

Some growers employ mealybug killers. Their job is to scrape the mealybugs off the plants. The little bug has red blood, which is used as a red dye. I once had a call from a lady who was frantic. She said her cactus plant was bleeding to death...said there was red blood all over the plant! It took me at least 10 minutes to convince her that cactus plants do not have red blood inside them. Her plant was totally infected with mealybug and could not be saved.

Do not let mealybugs get a start in your greenhouse or in your potted plant display in the dining room. They can take over the whole place in a week. 1999, Arizona Cactus.

For an autographed copy of David L. Eppele's On The Desert, Volume 2 send a check for $17.00 to Arizona Cactus, 8 Cactus Lane, Bisbee, Arizona 85603. Cactuseros will delight in learning that the book was banned in Spain days before publication:) Eppele said the book may also be banned in Colombia and parts of Nebraska.


From the St Louis Newsletter

Plant of the Month by Leo Martin

Monvillea (Britton and Rose, 1920)

Britton and Rose named this genus after Parisian cactus dealer Monville, who had earlier named several species as members of genus Cereus. They are from central South America, from southern Brazil into Venezuela. Clambering, vining cacti, they posses relatively small but very effective spines. Found growing through trees and shrubs, shaded by the leaves, in Phoenix they do well in dappled to full shade, though tolerating full sun if moved gradually. They tolerate little or no frost, appreciate warmth in winter, and will grow all winter if kept warm, watered, and brightly lit. In the summer they grow fastest with plenty of water. Flowers in abundance are white to pinkish, nocturnal, and long-tubed, reminiscent of Peniocereus but held laterally rather than upright. Fruits are red, and M. spegazzini , at least, is self-fertile in my collection.

Familiar species include M. spegazzini , with marbled grey and purple stems, and its crested form; and M. cavendishii, with solid green stems, somewhat larger in scale than M. spegazzini .


From the St Louis Newsletter

Plant of the Month by Leo Martin

Notocactus and its allies (Karl Schumann, 1898)

From central-southern South America come members of genus Notocactus in Greek, noto- means back or (bony) spine; the tubercled ribs may resemble the spine in your back. They are globular to low columnar with characteristically depressed centers, usually many ribs, and usually many fine spines. The flowers tend to be yellow, in profusion, with red stigma lobes, and are borne on the upper "shoulders" of the plants in spring. Seed capsules retain the dried flower and are dry and papery when ripe. The seeds frequently fall next to the mother plant and germinate there.

Genus Notocactus comes mostly from grasslands with substantial summer and some winter rain. Like many grassland plants they don't do well in full sun in Phoenix, appreciate non-porous pots with some humus in the soil, and extra water. They also seem to appreciate more fertilizer than some cacti. They bloom young, prolifically, and easily if not kept dry in the winter. They set seed readily.

Once separate genera but now included in Notocactus were Brasilicactus, Eriocactus, Malacocarpus, and Wigginsia. Closely related is Parodia, which comes from somewhat higher and dryer locales than Notocactus.


From the St Louis Newsletter

How are plants named? Part One: Why two names? by Leo Martin

When talking about something, people need to agree on what they are discussing. That's one reason we name things. So it is in the world of biology. Scientists need to be able to discuss living things no matter what language the scientists speak, and be sure everybody understands what organism is being discussed. For this reason rules have been set for how to name plants so everybody knows which plant is being discussed when botanists gather.

For example, suppose somebody asks you how to take care of a cactus. You might ask which one. The person says, "Well, it is green and has long spines." You won't be able to help as much as if you knew exactly which plant it is.

Or, suppose the question is "Where do I get a night-blooming Cereus?" There are dozens of cacti that have white flowers and bloom nocturnally. Which one is meant?

Botanists group plants mainly according to differences in reproductive structures, including flowers, fruits, and seeds. I'll go into why in the next article, but for now, these structures seem to be less variable among closely related species than do such things as color and size.

Seed-bearing plants are divided into two large groups, the gymnosperms (naked seeds), which includes conifers, cycads, Welwitschia, and Ephedra, and angiosperms (vascular seeds.) Angiosperms are plants with typical flowers and seeds clothed with some kind of fruit. Cacti are angiosperms. Angiosperms are divided into monocotyledons, having one leaf (cotyledon) emerging from the seed like grasses, palms, and aloes, and dicots, having two cotyledons, like beans, roses, and cacti. Cacti are distinguished by petals attaching above the ovaries, and the presence of the areole, a special structure containing two growth tissues which may form spines (modified leaves), flowers, or another shoot.

A species is the entire worldwide group of individual organisms that are substantially similar, almost identical, to each other, that are able to reproduce with each other. An example would be all the saguaros in the world; they are all one species. Other similar cacti (cardon) are not that species though they look somewhat similar.

Species that are clearly similar to each other are grouped into genera (singular genus.) All members of a genus will be substantially similar to each other, though substantial differences will exist. The first part of a plant name is the genus; for example, Ferocactus. It is always capitalized and italicized when printed. Think of the genus name as the plant's last name.

Each species (species is singular and plural; specie is precious metal money) in a genus will have its own name as well. This name is written second, and is always italicized and never capitalized. Think of this as the plant's first name; an example would be two Arizona barrel cacti, Ferocactus cylindraceus (found in the Phoenix area) and Ferocactus wislizenii (found in the Tucson area.)

Knowing the correct names of plants allows us to be specific. It is easier to say Ferocactus cylindraceus than it is to say "the thin, short reddish-spined barrel cactus that grows around Phoenix."

Botany books contain chapters on various genera. They usually start by describing the genus and how it differs from related genera. Then there will be a key, which shows the differences between the species in that genus. Having a specimen at hand, especially the flower, one can use the key to identify the species of the plant. Then will follow more detailed descriptions of the species.


From the St Louis Newsletter

How are plants named? Part two: What are the naming rules, and where did they come from? by Leo Martin

Humans have been interested in plants at least as long as we have been writing, and almost certainly longer. Roman naturalists wrote of plants of economic, medicinal, or curiosity value. Herbals from the European Medieval period were based mainly on the much older Materia Medica by Dioscorides. They show drawings of plants and descriptions in Latin, often several lines long. They mainly focused on medicinal plants.

In the European Renaissance period, naturalists noticed that organisms of all kinds were related to others of their kinds. They sought systematic naming arrangements to reflect this. In the plant kingdom, it became apparent to botanists that flower and fruit structures were usually much less changeable among similar plants than were leaf, stem, or root structures. For example, think of genus Euphorbia: All the flowers are structurally very similar, though the plants themselves vary wildly from species to species. By the end of the Renaissance, naturalists realized that species fell into naturally related groups, or genera (singular, genus.)

Karol Linne (Latinized to Carolus Linnaeus) was professor of natural history at the University of Uppsala in Sweden in the mid 1700s. He devised the current system. Plants were to be given two names, one representing the genus, and the other the species. Similar species were grouped into the same genus. The names were to be derived from Greek or Latin words, were to be mainly descriptive, and were to be italicized when written. Groups of genera related to each other were to be included in families.

The next discovery in natural history was cataclysmic and upset the entire Western world order. But more about this in another article. This system has been used ever since. The rules for naming new discoveries are altered from time to time by the International Botanical Congress (IBC), which meets quadrennially (the 1999 meeting just finished at the Missouri Botanical Garden.) Here is a brief condensation of the rules for naming newly discovered plants:

1) A plant must have a description and name published in an article in a scientific publication.

2) The description, called a diagnosis, must be in Latin, and must explain how the plant differs from closely related plants, and must give descriptions of all the parts of the plant. The rest of the article may be in any language. The description must give the genus in which the author thinks the new species belongs. If the plant represents a new genus, the description must state how the genus differs from similar genera.

3) The species name (specific) is given by the author. It is Latinized. The grammar must be correct (gender of genus and species must agree.) It may be descriptive of some aspect of the plant; it may honor another person; or, it may be anything the author wishes. The specific may not have been used before for a plant in that genus. If the plant is in a new genus, the author may choose the new generic name as well. For a new genus, a type species must be designated typifying characteristics of the new genus.

4) A type specimen of the plant must be deposited in an herbarium accessible to scholars for examination. The specimen must include all parts of the plant (roots, stems, leaves, flowers, fruit) or the plant may not be officially described.

5) The location where the plant was found must be published.

6) If any of these rules are not followed, the publication is invalid. If the author notices the error(s), they may be corrected in print, usually the same publication, and the name stands. If another author notices the error(s) first and publishes a correct description, the correcting author may give another name. If this is done, the first author's species name may never be used for another species in that genus, or for another genus if it was a description of a genus.

7) If a genus or species name has already been used, and an author uses the name for another plant, the first publication takes precedence when the error is discovered, and the subsequent plant(s) described under the name must be renamed.

8) A plant named properly under the rules in force at the time of naming retains its name if the rules change in the future in such a way that the original description would have been inadequate had the new rules been in force.

On rare occasions the International Botanical Congress votes to ignore the rules, for example, when a genus name is given a second time and becomes widely recognized before an obscure prior genus naming is discovered. This happened with Mammillaria, which was first given to algae in an obscure publication, and then given to the cacti. Since the cacti were widely known as Mammillaria, the IBC voted to conserve the name for the cacti.

The first cacti came to Europe from the shores of the Caribbean islands. We now call them Melocactus. Linnaeus knew immediately they were members of a group never seen by Europeans, and he coined the genus Cactus for them. Kaktos was Greek for the thistle, which has sharp spines. As more cacti were discovered, it was realized there should be more than one genus for them. Soon the columnar ones were transferred into genus Cereus, from the Latin for candle, and the globular ones to Echinocactus , from Greek echinus, spiny. Soon even more genera were described. Species were transferred from one genus to another, a process that continues to this day. Why?

Sometimes the author of a genus or species had not done requisite homework and used a name already given. This was not always sloppy work; many plants were published in small journals with small circulations and did not become known to the general naturalist community. In this case the first publication is considered correct and the second name, if a generic, may never be used again in the plant kingdom, and if a specific, may not be used again in the genus.

Sometimes the original publication did not include all the requisite parts and nobody noticed at the time. In this case, whoever corrects the publication may name the plant. If the correcting author renames the plant, the first name may never be used again if it were a genus, and may never be used for a species in the given genus if it were a species name. Caution is necessary here; the rules in force at the time the publication was made are applicable, not the most recent rules.

Sometimes, with more fieldwork, it is believed that authors made errors in assigning species to genera or in dividing genera into more genera. In this case, an author may name a new genus following the current rules, and may transfer what species fit into that genus. Normally, the species names will be retained, with the gender changed if necessary to agree with the genus, though this is not necessary. Interestingly, English authors correcting Germans seem never to retain the German names. If the genus already includes a species with the same name as one being transferred into the genus, the incoming plant requires a new name.

Sometimes, with more fieldwork, it is realized that the same species has been given more than one name. This happens commonly with plants having wide distribution and substantial variability from locale to locale. In this case, an author reduces the various species names to synonymy, and the first name given to the plant is considered correct. The subsequent names erroneously given to the same plant may never be used in that genus again.

An example of serious name change is the genus now known as Pilosocereus. Botanist Haworth named Cactus senilis (senilis = old man.) In 1838 Pfeiffer split off Cephalocereus (head Cereus) from Cactus and designated Cephalocereus senilis as the type species for the new genus. The next year, Lemaire described genus Pilocereus (hair Cereus) and gave what had been Cactus senilis as the type species, either not realizing or ignoring that Pfeiffer had already designated Cactus senilis as type species for Cephalocereus. This violated naming rules, which was soon recognized, as was the fact that Cephalocereus and Pilocereus were not closely related at all. Schumann in 1898 tried to rectify the situation by publishing genus Pilocereus excluding its type, but this was against the rules as well, and the ICB voted it down. Then, in 1955 and 1957, Byles and Rowley published generic name Pilosocereus (hairy Cereus) for these plants, naming what Poselger had called Cereus leucocephalus (white head Cereus) as the type.

Basically, names should be changed as a result of better understanding natural populations of species and their relations to other species. Name changes are to be expected; they reflect more careful fieldwork. But, authors changing names sometimes fail to follow the rules. An example is the natural hybrid of Pachycereus pringlei and Bergerocactus emoryi: It was named correctly by Moran as Pachgerocereus orcuttii according to the rules then in force. Soon thereafter the ICBN specified that natural hybrid genera should have names composed of approximately half from each parent genus. A British author published a name change, to Pachgerocactus. But this second name is unwarranted because the plant was named properly according to the rules in force when it was named.

There's no need to rush to change labels when you hear of a name change. There is no central botanical authority that votes on correct names. Name changes are accepted over time if professional botanists accept the reasoning of authors making changes. If you don't accept the reasoning, you don't have to change. The only time ICB votes is when requests are made to do things deliberately against the accepted rules.

Part of the reason cactus nomenclature is so mixed up is that much of the original work and naming was done by amateurs without proper training. Many mistakes were made, and generally far too many minor variants were given generic and specific names. Many species were described from sterile specimens (in taxonomy, this means an herbarium specimen without flowers and fruit.) Since flower and fruit morphology are considered most important in separating species, one can see sterile specimens are not useful. Many type specimens were deposited in herbaria destroyed during WW II and many of these "species" have not been rediscovered. Are they extinct, or were they incorrectly described? We don't know. For these reasons, and others, many professional taxonomists (taxon=Greek for named group; taxonomy=the study of naming organisms) do not wish to work with the mess that is cactus nomenclature.