Topic
Cereeae
About: Cereeae is a research topic. Over the lifetime, 13 publications have been published within this topic receiving 445 citations.
Papers
TL;DR: The purpose of this article is to present briefly current theories concerning the morphology of the cactus gynoecium and, primarily, to introduce placentation of the conventional parietal type, or is it a highly derived and modified type, which gives a false impression of simplicity?
Abstract: Although taxonomists interpret the ovaries of most cacti as inferior,3 the inferior position has been derived in a very different manner from that in most flowering plants. In the classical situation, the dorsal sides of connate carpels are invested by a floral tube (hypanthium); in Cactaceae, on the other hand, the dorsal sides of the carpels are mostly free-not invested by a floral tube. The ventral sutures are pulled downward during formation of the hollow receptacle so that they come to lie on the sides of a locule between flanges of tissue which represent the reduced remains of fused margins and lateral walls of adjacent carpels. The morphology of an individual carpel is like that of a pea pod which has been split midway between dorsal and ventral bundles, then opened up so that the dorsal segment projects upward, the ventral segment containing the ovules, downward. In most cacti, the ventral segments are adnate to the walls of a hollow floral receptacle. In all cases observed so far, the floor of the locule appears not to be invested by carpellary tissueit is interpreted here as representing free receptacular tissue. In other words, the morphological bases of cactus carpels are not at the bottom of the locule, but above it, where the dorsal and ventral bundle systems diverge from the recurrent receptacular bundles. This interpretation, like the more complex one offered by Buxbaum, explains the commissural stigmas reported by Tiagi for Opuntia and Mammillaria. IN TWO EXTENSIVE reviews, Douglas (1944, 1957) has summarized the literature on the inferior ovary and the varying opinions that have been held concerning its nature. Both she and, more recently, Eames (1961, p. 245) have pointed out that in most cases the gynoecium is enclosed by the bases of connate outer floral parts-the outer tissues of the ovary are appendicular. Cactaceae, on the other hand, provide one of the few exceptions to this general rule, for there seems to be universal agreement that in this family the gynoecium is sunken in the end of a modified branch-the outer tissues of the ovary are receptacular. In the interpretation of other structural features of the cactus gynoecium, however, there is no general agreement. Is placentation of the conventional parietal type as is generally implied in taxonomic treatments, or is it a highly derived and modified type, which gives a false impression of simplicity? An answer to this question is imperative before the morphology of the cactus carpel and its parts can be understood and compared with carpels of other families. Such an understanding might prove to be of considerable assistance in determining the phylogenetic position of the family, concerning which there is likewise no agreement. The purpose of this article is to present briefly current theories concerning the morphology of the cactus gynoecium and, primarily, to introduce 1 Received for publication November 10, 1963. 2 This investigation was supported by a grant from the National Science Foundation. 3 The term "inferior" is preferable to "epigynous" because it has less definite morphological implications. It is doubtful that cactus flowers are truly epigynous. a new one, which I think has the virtue of simplicity. Furthermore, the new interpretation is supported by 3 somewhat different, yet complementary, approaches to the investigation of structure: developmental anatomy, vascular anatomy, and comparative morphology. Because the article is largely theoretical, there will be no meticulous attention to anatomical detail. This is not a study of the flower of any one species, genus, or other taxon. It is the presentation of a general picture, which I hope will serve as a foundation for more detailed studies in the future. MATERIALS AND METHODS-The materials used in this study have come to a large extent from a cactus collection which I have been accumulating for a decade. The original specimens were collected in the field, purchased from commercial collectors, or sent to me by friends who are engaged either in cactus culture or research. Ladislaus Cutak and Harry Johnson have provided live cuttings of various pereskias; Dr. I. W. Bailey has supplied preserved materials. Each of these persons has obtained his specimens from sources unknown to me. The specific identifications are, to the best of my knowledge, correct. However, misidentifications at the specific level would not alter the conclusions presented in this paper. For the higher cacti (the non-leafy cacti, which belong to the tribes Opuntieae and Cereeae), it has been convenient to use microslides and embedded tissues employed in previous investigations dating back to 1950. All specimens were prepared for histological study by the usual paraffin method. Clearing of floral buds and flowers was done with lactic acid by modification of a technique deseribed bv Bebhnham (1939).
46 citations
TL;DR: Assessment of the phylogenetic relationships between tribes Cereeae and Browningieae in the cactus subfamily Cactoideae found members of each tribe resembled each other more than they resembled any member of the other tribe.
Abstract: The purpose of this study was to assess the phylogenetic relationships between tribes Cereeae and Browningieae in the cactus subfamily Cactoideae. During field trips to Venezuela, Ecuador and Chile, tissue samples were collected from representative specimens in natural populations. Monvillea* diffusa, M. maritima, and M. smithiana were virtually identical anatomically and, although similar to Cereus hexagonus, they were distinct in having large druses in their outer hypodermis and extremely small wall crystals in their cortex. Pilosocereus mortensenii was indistinguishable from the samples of Subpilocereus* (S. ottonis, S. repandus, S. russelianus) but was very different from other pilosocerei (P. lanuginosus, P. moritzianus, P. tillianus). Samples of Subpilocereus, including P. mortensenii, were similar to those of C. hexagonus in having no hypodermal crystals, no druses in pith or cortex, few or no mucilage cells in pith or cortex. Anatomical characters supported a hypothetical close relationship between Armatocereus (A. brevispinus, A. cartwrightianus, A. godingianus) and Jasminocereus (J. thouarsii), but Jasminocereus had few distinctive features that could be used to link it strongly to any genus in this study. Both tribes were variable, but members of each resembled each other more than they resembled any member of the other tribe. Leptocereus quadricostatus (tribe Echinocereeae) did not obviously share more characters with one tribe versus the other. Pachycereeae are more similar to Cereeae than to Browningieae.
37 citations
TL;DR: The anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species of Arrojadoa, Stephanocereus and Brasilicereus are described.
Abstract: (Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger wâBrasilicereus Backeberg). Arrojadoa, Stephanocereus and Brasilicereus are endemic Brazilian Cereeae, occurring along the Espinhaco Range, in the campos rupestres, cerrados and caatingas, from northern Minas Gerais to southern Bahia. The genera are columnar, erect to semi-erect cacti, except for one species, A bahiensis, which is globose. This study describes the anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species. Basal portions of stems were sectioned transversely and longitudinally, and stained with Astrablue and Safranin. The species share a uniseriate epidermis, with thick cuticle; well developed collenchymatic hypodermis, containing prismatic crystals; cortex with numerous mucilage cells, druses and vascular bundles; outside cortex as a palisade parenchyma; periderm composed of lignified cork cells alternating with suberized cells; pheloderm consisting of a few layers of thin-walled cells; phloem composed of solitary or multiple of two to three sieve tube elements, companion cells, axial and radial parenchyma; secondary xylem with solitary to multiple vessels, with simple perforation plates and alternate bordered to semi-bordered pits; axial parenchyma scanty vasicentric to incomplete; libriform septate fibres; large rays. Unlignified parenchyma is seen in the secondary xylem, varying from a few cells to bands among axial and radial elements. The following are considered diagnostic characters: the shape of lignified phellem cells, cubic to radially elongate, which individualizes S. leucostele; an underdeveloped hypodermis and the occurrence of sclereids in the cortex are exclusive to Brasilicereus markgrqfii.
31 citations
TL;DR: The phylogenetic distribution of two deletions within the chloroplast trnT–trnL intergenic spacer suggested that Browningieae, a tribe defined largely by shared primitive features, were not monophyletic, and that Harrisia may have been incorrectly placed outside the BrowningIEae–Cereeae–Trichocereeae group.
Abstract: The phylogenetic distribution of two deletions, of about 350 and 250 bp respectively, within the chloroplast trnT–trnL intergenic spacer was examined. One deletion was found in all members of Cactaceae subfamily Cactoideae sampled, totaling 37 species, but not in taxa from other subfamilies or closely related families. The second was shared by a subset of Cactoideae comprising members of tribes Cereeae, Trichocereeae, and Browningieae (in part), as well as Harrisia. Close links among the former three South American tribes have been previously hypothesized. This distribution suggested that Browningieae, a tribe defined largely by shared primitive features, were not monophyletic, and that Harrisia may have been incorrectly placed outside the Browningieae–Cereeae–Trichocereeae group.
28 citations
TL;DR: A new species of tropical Pilosocereus is relatively bat-specialised, this Cereeae genus is more flexible in its pollination system than the Pachycereeae genera and shows more affinity with other columnar cacti from tropical regions than with those from extratropical regions.
Abstract: It has been suggested that there is a geographic dichotomy in the pollination systems of chiropterophilous columnar cacti: in intra-tropical areas they are pollinated almost exclusively by bats, whereas in extratropical areas they are pollinated by bats, birds and bees. However, currently the studies are clumped both taxonomically (mainly Pachycereeae species) and geographically (mainly in the Tehuacan Valley and the Sonoran Desert). This clumping limits the possibility of generalising the pattern to other regions or cactus tribes. Only four of the 36 chiropterophilous cacti in Pilosocereus have been studied. Despite the tropical distribution of two Pilosocereus species, bees account for 40-100% of their fruit set. We examined how specialised is the pollination system of P. leucocephalus in eastern Mexico. As we studied tropical populations, we expected a bat-specialised pollination system. However, previous studies of Pilosocereus suggest that a generalised pollination system is also possible. We found that this cactus is mainly bat-pollinated (bats account for 33-65% of fruit set); although to a lesser degree, diurnal visitors also caused some fruit set (7-15%). Diurnal visitors were more effective in populations containing honeybee hives. P. leucocephalus is partially self-compatible (14-18% of fructification) but unable to set fruit without visitors. Despite the variation in pollination system, P. leucocephalus shows more affinity with other columnar cacti from tropical regions than with those from extratropical regions. Although we report here that a new species of tropical Pilosocereus is relatively bat-specialised, this Cereeae genus is more flexible in its pollination system than the Pachycereeae genera.
27 citations
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| Year | Papers |
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| 2015 | 1 |
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| 2004 | 1 |