Default image for the object Heteromorphism in seeds of Leptocereus scopulophilus (Cactaceae) from Pan de Matanzas, Cuba, object is lacking a thumbnail image
Seed heteromorphism is the formation of different seed morphs from the same individual. Two seed morphs have been preliminarily observed in Leptocereus scopulophilus. One morph shows an apparent natural scarification of its coat. Herein we describe the seeds, taking into account shape, coat integrity, surface, dimensions, mass and the position of germination cracks. We defined two seed morphs using the integrity of the spermoderma: fragmented seed coats (FSC) and complete seed coats (CSC). We also evaluated minimum germination time, germination rate and germinability. The seed morphs did not differ significantly in traits; however, regular striations along the cuticle of the periclinal walls were more visible in the FSC compared with the CSC. Both seed morphs displayed anticlinal cell boundaries in the border region that are channelled and straight in the dorsal-ventral region but difficult to define in the lateral region. We found four morphological variations in different positions where the radicle or cotyledons emerge and variations in cuticle thickness in different regions of the seed that could determine the formation of cracks during germination. All germination variants occurred in both seed morphs, albeit in different proportions. Germination was higher and faster for the FSC compared with the CSC. These germination differences could be related to a thinner cuticle in the FSC and the punctual release of its spermoderma, which facilitates a quick imbibition of the embryo and the breaking of the seed coat. Our results indicate that differences in germination parameters between the two seed morphs relate to differences in the percentage of dormant seeds, which favour the temporal expansion of germination and reduce competition between siblings. To propagate the species for conservation purposes, we recommend using FSC, while CSC may be used to establish a seed collection ex situ.
Leptocereus, a genus with its centre of diversity in Cuba, has about five different assemblages of species based on floral features. However, flowers are not always available when identifying plants. Considering wood as a conservative tissue and its previous contributions to the taxonomy and systematics of flowering plants, the wood anatomy of L. arboreus and L. scopulophilus is described and compared with other species of the genus. In wood anatomy, L. arboreus, from central Cuba, differs from the western species by the presence of scalariform intervessel pits, a feature also reported for L. quadricostatus, a species of Puerto Rico and the British Virgin Islands. This fact might indicate that L. arboreus is probably more similar to the eastern species of the genus. Leptocereus scopulophilus is characterized by the predominance of septate fibres and solitary vessels. All the studied Cuban species of Leptocereus have druses in ray cells, a distinct characteristic in Cactoideae.
Vivipary is the germination of a seed inside of a fruit before it is separated from the mother plant. In the present study, the populations of several Cuban cactus species are explored in search of vivipary and Leptocereus scopulophilus is used as a model species to evaluate the effectiveness of vivipary in the establishment of offspring. Vivipary is a relatively common phenomenon in Cuban cacti from different ecosystems with variable temperature, rainfall and salinity, whose frequencies of population vivipary and average of viviparous seedlings per fruit are usually low. In L. scopulophilus, vivipary does not constitute a more efficient reproductive strategy that favors establishment, which is typically the limiting factor for the perpetuation of viviparous species. On the other hand, viviparous seedlings will be favored in environments with high levels of humidity and availability of safe sites, which are sporadic in semiarid environments.
Origin Information
Default image for the object The programme for the conservation of Cuban cacti: Achievements and challenges, object is lacking a thumbnail image
A brief summary of the progress made in the conservation programme for the threatened cacti of Cuba. Photography by the author. [ABSTRACT FROM THE AUTHOR]
Origin Information
Default image for the object Conservation of Leptocereus scopulophilus and L. wrightii, two endemic cacti from Cuba, object is lacking a thumbnail image
Two extremely rare leptocerei from Cuba, in imminent danger of extinction in the wild, are the subject of a survey supported with finance from the BCSS Conservation Fund. Photographs supplied by the authors.
Origin Information
Default image for the object The ecology and natural history of Leptocereus scopulophilus (Cactaceae), object is lacking a thumbnail image
Some results of research on the ecology and natural history of Leptocereus scopulophilus(Cactaceae) in Cuba are presented. In so doing, it is hoped that this will stimulate additional new and innovative research into the entire genus Leptocereuswith a view to supporting further conservation efforts. Photography by the authors. [ABSTRACT FROM THE AUTHOR]
Origin Information
Default image for the object Vivipary in Cuban cacti: A pioneer study in Leptocereus scopulophilus, object is lacking a thumbnail image
Vivipary is a relatively unusual trait in the angiosperms, documented in nearly 195 species of 78 vascular plant families, including 53 cactus species. In this paper we report the occurrence of vivipary in four Cuban cactus species (Leptocereus arboreus, L. scopulophilus, Harrisia eriophora and Selenicereus grandiflorus). For L. scopulophilus, we determined the frequency of vivipary and compared fruit traits in viviparous and non-viviparous fruits. We found that 18.9% of L. scopulophilus individuals had viviparous fruits. None of the fruit traits compared between viviparous and non-viviparous fruits differed significantly, although the pericarp is slightly thicker in viviparous fruits.
Origin Information
Default image for the object The role of mucilage in the germination of Leptocereus scopulophilus (Cactaceae) seeds from Pan de Matanzas, Cuba, object is lacking a thumbnail image
Studies of seed mucilage in a number of species suggest that it has multiple ecological roles dependent on species and their environmental context. We evaluate whether mucilage facilitates seed germination for Leptocereus scopulophilus Areces, as well as whether light conditions influence the effect of the mucilage. Three combined treatments of light conditions: (1) shade (10% of sunlight), (2) semi-shade (30% of sunlight), and (3) full light exposure (100% of sunlight), and two seed types (with mucilage and washed) were used. Germinability was affected by light conditions but no effect of mucilage was found; higher germination occurred in shade than in semi-shade conditions. There was no germination in full light conditions. Germination rate (T50) was not affected by light conditions or by the mucilage, or the interaction of both factors. Minimal time to germination (Tmin) was affected by mucilage; seeds with mucilage germinated 2 days later than washed seeds. Thus, facilitation for imbibition of water does not occur in L. scopulophilus seeds. Perhaps the presence of mucilage in seeds of this species serves other purposes such as seed adhesion to soil or to deter predators. [ABSTRACT FROM AUTHOR]
Los roedores son importantes depredadores de semillas dispersadas por otros grupos de vertebrados (Janzen 1986, Terborgh & al. 1993). No obstante, algunas especies de roedores pueden jugar un papel importante como dispersores secundarios de algunas especies de plantas, al acumular y enterrar semillas en sus madrigueras (Forget & Milleron 1991, Wang & Chen 2009). Incluso, existen evidencias de endozoocoría por algunas especies de ardillas (Corlett 1998) y ratas (Williams & al. 2000), que pueden tragar semillas pequeñas y defecarlas intactas; aunque se conoce que el paso de las semillas por el tracto digestivo en estos roedores puede tener un efecto inhibidor sobre la germinación (Traveset 1998).