Différences
Ci-dessous, les différences entre deux révisions de la page.
Les deux révisions précédentesRévision précédenteProchaine révision | Révision précédenteDernière révisionLes deux révisions suivantes | ||
backebergia_militaris [2010/04/19 19:44] – alain | backebergia_militaris [2010/04/19 19:53] – alain | ||
---|---|---|---|
Ligne 738: | Ligne 738: | ||
adaptation, and successfully complete their life cycle. | adaptation, and successfully complete their life cycle. | ||
- | ====== PARASITIC SYMBIOSES | + | ===== PARASITIC SYMBIOSES ===== |
Carrying out observations in the field and on sectioned | Carrying out observations in the field and on sectioned | ||
Ligne 781: | Ligne 781: | ||
contemplating also the presence of natural parasites. | contemplating also the presence of natural parasites. | ||
- | ====== MUTUAL SYMBIOSES | + | ===== MUTUAL SYMBIOSES ===== |
With the publication of Holland & Fleming’s work | With the publication of Holland & Fleming’s work | ||
Ligne 1033: | Ligne 1033: | ||
ies, carried out also on a genetic basis, and extended to | ies, carried out also on a genetic basis, and extended to | ||
the whole distribution area. | the whole distribution area. | ||
+ | |||
+ | ====== | ||
+ | |||
+ | Colima: | ||
+ | - not confirmed. Jalisco: Pico de Colima (Lemaire, 1847, | ||
+ | perhaps today’s Nevado de Colima), probably referred to | ||
+ | the nearby location of Jilotlán de los Dolores (Chazaro, | ||
+ | 1995 and Jean-Marc Chalet, pers. comm.) Michoacán: | ||
+ | Type Locality: | ||
+ | Apatzingán and, more to the south-east, the ‘Infiernillo’ | ||
+ | dam (H. Bravo-Hollis, | ||
+ | Cinco de Mayo (Jean-Marc Chalet, 2003). | ||
+ | Basin of the Balsas River – several locations (not specified, | ||
+ | Anderson 1994), perhaps relative to Ciudad Altamirano | ||
+ | (H. Bravo-Hollis, | ||
+ | H. Bravo-Hollis, | ||
+ | (it is outside the species’ area of distribution) | ||
+ | |||
+ | ====== Historique ====== | ||
+ | |||
+ | The many changes in status and synonymy, and nomenclatural mistakes regarding Backebergia place it among the first positions in the Guinness of taxonomical rebuses. | ||
+ | |||
+ | 1836/ Pilocereus militaris Hort. | ||
+ | 1839 militaris = for the resemblance of the inflorescence to the hel- | ||
+ | met of English grenadiers, | ||
+ | quoted in Förster, C. - Handbuch der Cacteenkunde, | ||
+ | (1886). | ||
+ | Year of the discovery of the species, by the explorer Joseph | ||
+ | Vandick from Antwerp, who collects some specimens and | ||
+ | sends them to the collector M. de Jonghe in Brussels. The | ||
+ | plants are observed by the French horticulturist M. Cels, who | ||
+ | gives them their first name. | ||
+ | 1845 Cereus militaris Audot - in Revue Horticole 2: 307 | ||
+ | The French horticulturist Audot writes the first valid descrip- | ||
+ | tion of the species. | ||
+ | 1845 Pilocereus niger Neumann - in Revue Horticole II, 2: 289 | ||
+ | In the same publication the botanist Neumann describes a new | ||
+ | cactus species seen at the Jardin des Plantes in Paris. They are | ||
+ | samples donated by the Mexican politician and naturalist | ||
+ | Melchor Ocampo, belonging to the same species discovered by | ||
+ | Vandick. | ||
+ | 1847 Pilocereus chrysomallus Lemaire, in Flore des Serres et des | ||
+ | Jardins de l’Europe 3: 242 | ||
+ | chrysomallus = with a yellow head | ||
+ | M. Galeotti’s herbarium is enriched with some cactus samples | ||
+ | coming from the locality “Pico de Colima” (perhaps today’s | ||
+ | Nevado de Colima in Jalisco). Lemaire doesn’t recognize the | ||
+ | same species described by Audot and Neumann and writes a | ||
+ | new description. | ||
+ | 1849/ Pilocereus militaris Hort. ex Salm-Dyck, in Cact. Hort. Dyck. | ||
+ | 1850 ed. II. 40. Invalid name | ||
+ | 1880 Cereus chrysomallus | ||
+ | Centrali-Americani, | ||
+ | Hemsley includes | ||
+ | Cereus, creating a new combination of Lemaire’s name. | ||
+ | 1894 Cephalocereus chrysomallus (Lemaire) Schumann, in Engler | ||
+ | et Plantl, Pflanzenfam. 3 (6°), 182 | ||
+ | Schumann recombines Pilocereus chrysomallus as Cephalocereus | ||
+ | chrysomallus and places | ||
+ | chrysomallus Hemsley and Pilocereus chrysomallus as syn- | ||
+ | onyms. Pico de Colima becomes the type locality for the species. | ||
+ | 1920 Pachycereus chrysomallus | ||
+ | 1847, in The Cactaceae, Washington DC | ||
+ | Britton & Rose reckon that Pilocereus fulviceps Weber (Cereus | ||
+ | fulviceps | ||
+ | species described as Pilocereus chrysomallus by Lemaire and | ||
+ | coming from Pico de Colima. When they create the new genus | ||
+ | Pachycereus they include also Pilocereus fulviceps | ||
+ | with the wrong name “chrysomallus” belonging to the plant | ||
+ | described by Lemaire, and therefore they place in synonymy | ||
+ | Pilocereus chrysomallus | ||
+ | Hemsley, | ||
+ | fulviceps Weber and Cereus fulviceps Berger. They include in | ||
+ | the list also Cereus militaris | ||
+ | Schumann as probable synonyms. | ||
+ | 1942 Mitrocereus chrysomallus Backeberg - in Cact. J. DKG, 48: 77 | ||
+ | Curt Backeberg reckons that the formation of the cephalium, | ||
+ | characteristic of the species from Tehuacán (Pilocereus fulvi- | ||
+ | ceps Weber), is a character sufficient to separate it from | ||
+ | Pachycereus, | ||
+ | subgenus Mitrocereus, | ||
+ | Also Backeberg’s work is based on Britton & Rose’s erroneous | ||
+ | description; | ||
+ | mens and uses the epithet Pilocereus chrysomallus. | ||
+ | date Backeberg raises subgenus | ||
+ | genus and the type species becomes Mitrocereus chrysomal- | ||
+ | lus: Britton & Rose’s species from Tehuacán. | ||
+ | 1953 Backebergia chrysomallus | ||
+ | Biol. Mex. 24:230 (1953) | ||
+ | Helia Bravo-Hollis rediscovers the species after almost 106 years | ||
+ | and decides to rename it on the basis of Lemaire’s description | ||
+ | of Pilocereus chrysomallus, | ||
+ | and therefore creating a new monospecific genus. | ||
+ | 1961 Mitrocereus militaris (Audot) H. Bravo ex Buxbaum, in Bot. | ||
+ | Stud. 12: 54 | ||
+ | Buxbaum declares that the species | ||
+ | Lem., on which Bravo’s description is based, is a nomen con- | ||
+ | fusum and renames the species according to the rules of | ||
+ | nomenclature, | ||
+ | ered valid. | ||
+ | 1973 Backebergia militaris | ||
+ | Mejorada, in Cact. & Succ. J. US 155: 171 | ||
+ | Sanchez-Mejorada points out that Buxbaum has wrongly | ||
+ | referred to the name of a genus attributed to another species. | ||
+ | However, he agrees with the need of abandoning the specific | ||
+ | name chrysomallus. He adopts again the name Backebergia | ||
+ | associating it with the specific name militaris. | ||
+ | 1975 Cephalocereus militaris (Audot) H.E. Moore, in Baileya 19 (4): 166 | ||
+ | Moore follows D. Hunt in widening the genus Cephalocereus, | ||
+ | and includes in it Backebergia militaris together with | ||
+ | Mitrocereus fulviceps. | ||
+ | 1987 Pachycereus militaris (Audot) D. Hunt, in Bradleya 5: 93 | ||
+ | David Hunt makes up for Britton & Rose’s mistake, recognizing | ||
+ | as valid the inclusion of the species in their genus Pachycereus | ||
+ | and Audot’s specific epithet. He does not offer any justification | ||
+ | for such a revision. | ||
+ | |||
+ | ====== WHERE DOES IT COME FROM? ====== | ||
+ | |||
+ | Among the species closest to B. militaris there | ||
+ | could be Pachycereus pecten-aboriginum. The | ||
+ | young seedlings of the two species are quite simi- | ||
+ | lar (Fig. 13 B. militaris, Fig. 14 P. pecten aborigi- | ||
+ | num): very large cotyledons, 7-8 ribs, numerous | ||
+ | white acicular spines. | ||
+ | Both P. pecten-aboriginum (on the left) and B. | ||
+ | militaris (on the right) would have originated from an ancestor with spiny fruits (A). In B. mili- | ||
+ | taris, the formation of the inflorescence occurred | ||
+ | thanks to the co-evolution with a lepidopteran | ||
+ | insect, through the stage of a pseudo-tiponche (B) | ||
+ | (similarly to what can be seen today in the species | ||
+ | Pachycereus schottii of Sonora), till it reached, due | ||
+ | to the greater and greater concentration of fertile | ||
+ | areoles at the apex of the stem (C), the stage of a | ||
+ | true tiponche. | ||
+ | The two evolutionary lines lead to opposite results | ||
+ | in the number and size of fruits and in the con- | ||
+ | centration of flowers along the stem. | ||
+ | |||
+ | |||
+ | ====== CEPHALIUM VS. PSEUDOCEPHALIUM VS. TIPONCHE ====== | ||
+ | |||
+ | In many cacti there is evident dimorphism between | ||
+ | sterile areoles, producing only spines, bristles and tri- | ||
+ | chomes, and fertile areoles, that can also produce a | ||
+ | flower bud. | ||
+ | In many species of small globular cacti the fertile areoles | ||
+ | completely substitute the sterile ones when the plant | ||
+ | reaches reproductive maturity. They can be distinguished | ||
+ | by their stronger and more conspicuous spines | ||
+ | (Coryphantha) or for their spines transformed in bristles | ||
+ | amidst abundant wool (Discocactus). In these cases, in a | ||
+ | specimen reaching reproductive maturity all the areoles | ||
+ | of the apical portion are different from those of the basal | ||
+ | one, with little alterations in stem morphology. In other | ||
+ | cases, the production of fertile areoles occurs only during | ||
+ | a certain phase (flowering period) of plant growth, after | ||
+ | which sterile areoles are produced again. In this instance | ||
+ | there is a false cephalium, formed by these groups of fer- | ||
+ | tile areoles, that may be lateral (Cephalocleistocactus | ||
+ | sensu Ritter) or apical (Arrojadoa, Stephanocereus, | ||
+ | Neodawsonia). | ||
+ | In other cases still, dimorphism does not refer only to the | ||
+ | areoles, but it also interests a portion of the stem, giving | ||
+ | rise to evident morphological changes. Two different | ||
+ | models may be distinguished: | ||
+ | cephalium. | ||
+ | The pseudo-cephalium has evolved independently in | ||
+ | some genera belonging to the tribes Pachycereae | ||
+ | (Cephalocereus) and Cereae (Micranthocereus, | ||
+ | Coleocephalocereus). It is the group of fertile, densely | ||
+ | pubescent areoles that develop preferentially along one | ||
+ | side of the stem of columnar cacti. There the cortex is fully | ||
+ | developed, and sometimes a thick periderm is produced, | ||
+ | which stiffens the epidermis and therefore inhibits photo- | ||
+ | synthesis. When present, the periderm is produced after the stem has fully developed, and fuses together all fer- | ||
+ | tile areoles. | ||
+ | The cephalium has evolved independently in some | ||
+ | genera belonging to the tribes Trichocereae | ||
+ | (Espostoa, Espostoopsis, | ||
+ | cereus) and Cereae (Melocactus). It is the group of | ||
+ | fertile, densely pubescent areoles that develop later- | ||
+ | ally on columnar species and on the apex of globu- | ||
+ | lar ones. It matures precociously (near the vegeta- | ||
+ | tive apex) and there the cortex soon stops thicken- | ||
+ | ing, so that growth is not congruous with the rest of | ||
+ | the stem (Mauseth, 1999). In the case of columnar | ||
+ | species the cephalium remains sunken in the stem, | ||
+ | while in the case of Melocactus, where it is apical, its | ||
+ | diameter is only a portion of that of the stem. | ||
+ | In comparison with the two cases described, the | ||
+ | inflorescence of Backebergia is morphologically | ||
+ | similar to the cephalium of Melocactus. However, its | ||
+ | ontogenetic characters bring it closer to a pseudo- | ||
+ | cephalium. Indeed in this case too, the stem of the | ||
+ | rachis can reach its maximum development in diam- | ||
+ | eter, analogous to that of the stem, before the pro- | ||
+ | duction of periderm (see the paragraph on tiponche | ||
+ | structure). | ||
+ | This analogy notwithstanding, | ||
+ | brings evidence to absolutely original morphologic | ||
+ | and functional factors (the phenomenon of ‘pro- | ||
+ | grammed’ detachment of the inflorescence, | ||
+ | that this implies), that lead me to consider the inflo- | ||
+ | rescence of Backebergia as a highly sophisticated | ||
+ | structure, NOT homologous to cephalium nor to | ||
+ | pseudo-cephalium. So original, indeed, as to | ||
+ | deserve a distinct definition. | ||
+ | For this reason I have chosen the term ‘TIPONCHE’ | ||
+ | (pron. Teepònche), | ||
+ | name with which the plants of B. militaris are com- | ||
+ | monly called in their distribution area. | ||
+ | |||
+ | ====== B. MILITARIS IN CULTIVATION ====== | ||
+ | |||
+ | After being rediscov- | ||
+ | ered by Helia Bravo- | ||
+ | Hollis, this plant has | ||
+ | attracted collectors, but | ||
+ | only at the beginning of | ||
+ | the ‘70s did the collection | ||
+ | and commerce of | ||
+ | tiponche cuttings start. | ||
+ | Probably, some expert col- | ||
+ | lector of botanical rarities | ||
+ | had noticed that a fallen | ||
+ | off branch with inflores- | ||
+ | cence could root and | ||
+ | grow normally. | ||
+ | It is reported that in | ||
+ | 1979, nurseries in | ||
+ | Texas, close to the | ||
+ | Mexican border, sold | ||
+ | hundreds of cuttings | ||
+ | with naked roots, or still to root. These plants were spread | ||
+ | here and there throughout the world, but at costs too high | ||
+ | for most of the common collectors, so that they became | ||
+ | the attraction of the local merchant, who could show off | ||
+ | his jealously kept and strictly not-for-sale specimen. | ||
+ | After a while, those who had the ‘luck’ of buying these inter- | ||
+ | esting plants soon found out that they were extremely difficult to | ||
+ | keep alive: after producing a few flowers, the plants did not keep | ||
+ | on forming the lovely inflorescence, | ||
+ | or they grew new branches quite similar to those of any cereus. | ||
+ | However, in most cases they stopped growing and the inflores- | ||
+ | cence died, leaving only, as a sad memory, a collapsed mass of | ||
+ | blackened bristles. | ||
+ | In view of what I have written above, it is easy to imagine that | ||
+ | these cuttings could not live for long: the high request for organ- | ||
+ | ic matter caused an immediate crisis, and it was no use for them | ||
+ | to elongate, trying to change a flowering branch into a photo- | ||
+ | synthetic one. | ||
+ | The Backebergia plant with no tiponche, instead, grows | ||
+ | without any particular problem. It can be treated as any colum- | ||
+ | nar species from the ‘hot’ tropics, such as Pilosocereus, | ||
+ | In order to flower, it needs a very tall greenhouse, where the | ||
+ | temperature must be high all around the year (young plants can | ||
+ | stand temperatures close to zero). The only known plant of this | ||
+ | species who has reached reproductive maturity in cultivation is | ||
+ | to be found in the botanical garden of La Habana, Cuba. Even | ||
+ | though the climatic conditions in Cuba are fine, the specimen is | ||
+ | kept in the greenhouse, probably to protect the cactus collection | ||
+ | from too much rain. This has certainly determined the success in | ||
+ | cultivation of this plant, known locally as the ‘Russian Soldier’, for | ||
+ | its tiponche. This is an interesting example, because it allows the | ||
+ | study of the life cycle of the plant in a location that is not subject | ||
+ | to the local climatic conditions. | ||
===== ACKNOWLEDGEMENTS ===== | ===== ACKNOWLEDGEMENTS ===== |