Mitotic and meiotic analysis of a pericentric inversion associated with a tandem duplication in Eleutherine bulbosa

The mitotic and meiotic chromosomes of five populations of Eleutherine bulbosa were analysed after C-banding and fluorochrome (DAPI/CMA) staining. All individuals showed heterozygosity in pair number I for a pericentric inversion and a tandem duplication in the inverted region of one of the homologues. The duplication comprised the secondary constriction and ca. 40% of its associated CMA⁺ heterochromatin. All the secondary constrictions were nucleolar organizers, but the repeated one seemed to be the most active. The inverted segment constituted ca. 70% of the chromosome length and included, in addition to the duplication and the centromere, two DAPI⁺ C-bands. These markers, especially the CMA⁺ blocks which were unique in the complement, permitted a detailed analysis of meiotic pairing. In practically all examples of late zygotene the CMA blocks were paired, which seems to mean that non-homologous pairing never occurred. At this stage the duplicated CMA⁺ block was clearly unpaired. At pachytene-diplotene the inverted region formed a typical loop without chiasmata. Although male meiosis was normal, no indication of sexual reproduction was found. A causal relationship between duplication, inversion and asexual reproduction is proposed to explain the maintenance of the heterozygosity.     

New Tigridieae (Iridaceae) from Mexico

A comparison of three heretofore undescribed species with the previously known species inTigridia subgen.Hydrotaenia suggests a realignment of taxa within the various complexes inHydrotaenia. Three species,T. venusta, T. illecebrosa, andT. catarinensis, and two subspecies,T. hallbergii ssp.lloydii andT. ehrenbergii ssp.flaviglandifera, are described.Sessilanthera citrina is described and the new taxonomic combinationS. heliantha (Ravenna) Cruden is proposed.     

Embryology ofCrocus thomasii (Iridaceae)

The embryology ofCrocus thomasii is described. Male meiosis is of simultaneous type, and gives rise to starchy microspores which develop into lipoid pollen grains; these are two-celled and show a spinulate acolpate, abaculate exine lacking apertures. The tapetum is glandular and its cells become bi- or sometimes multinucleate. The ovule is anatropous and bitegmic; the inner integument forms the micropyle. Megasporogenesis is heteropolar with starch accumulation in the functional chalazal megaspore. Embryo sac development conforms to thePolygonum type. The endosperm development is nuclear. The embryo develops according to the Caryophyllad type. In the ripe seed it is differentiated and enveloped by a starchy cellular endosperm. The embryological characters observed strongly favour a close relation betweenC. thomasii andC. sativus.     

A new species of Nemastylis (Iridaceae) from Mexico

A robust, yellow-floweredNemastylis from the state of Colima, Mexico, is described as new.     

Three new species of Tigridia (Iridaceae) from Mexico

Tigridia durangense, T. chiapensis, andT. huajuapanensis are described as new. The first species is known from llanos near La Ciudad and El Salto, Durango ; the second from the highlands of central Chiapas; and the third from a single locality near Huajuapan de León, Oaxaca.     

Leaf anatomy inTigridieae (Iridaceae)

A biometric study of theSarcocapnos crassifolia complex from eastern Andalusia (Spain), Algeria, and Morocco was carried out. Twentytwo populations were used in a principal components analysis based on 14 variables. The results support the recognition of two species,S. crassifolia andS. pulcherrima, spec. nova. The taxon described byBoissier asS. speciosa (S. crassifolia subsp.Speciosa) is maintained inS. crassifolia.     

The systematics of Rigidella (Iridaceae)

Rigidella and the four species contained therein are defined primarily on characters related to, and a direct consequence of, adaptation to hummingbird pollination. The genus is probably derived from either the “multiflora” complex inTigridia subgenusHydrotaenia or is an evolutionary line parallel toTigridia. Illustrations, distribution maps, and a key to the species are included. The rediscovery ofRigidella flammea Lindl. is reported, and a new species,R. inusitata, is described.     

Topoisomerase I inactivation by a novel thiol reactive naphthoquinone

The naphthoquinone adduct 12,13-dihydro-N-methyl-6,11,13-trioxo-5H-benzo[4,5]cyclohepta[1,2-b]naphthalen-5,12-imine (hereafter called TU100) contains structural features of both the anthracycline and isoquinone chemotherapeutics. An initial characterization showed TU100 is cytotoxic to mammalian cells and can inhibit topoisomerase I and II. Analysis using topoisomerase I now reveals TU100 is a slow acting inhibitor targeting the enzyme in the absence of DNA. Diluting pre-incubated TU100 and topoisomerase I failed to alleviate inhibition, suggesting the enzyme is being covalently modified. Critical cysteine thiols were identified as the possible target based on the ability of reducing agents to reverse TU100 inhibition. Consistent with this idea, TU100 protected topoisomerase I from inactivation by the sulfhydryl modifying agent N-ethylmaleimide (NEM). Unlike agents nonspecifically reacting with thiols, however, TU100 is specific for topoisomerase because it failed to inhibit a cysteine dependent protease. These results indicate TU100 is a novel naphthoquinone that inactivates free topoisomerase I via alkylation of cysteine residues.     

Xiphion heracleanum sp. nov. (Iridaceae) from Morocco

As a part of the revision of Xiphion (Iris subg. Xiphion) for the ‘Flora Iberica’ project, some material collected in the 19th and 20th centuries in the Tangiers area (northern Morocco) was found impossible to assign to any of the known taxa in the genus. In part, they resembled X. junceum and X. rutherfordii, but showed a peculiar combination of vegetative and floral characters which to date is exclusive. Accordingly, the new species X. heracleanum Mart. Rodr. & M. B. Crespo is described for these plants, and evidence is reported to justify the adopted treatment. Relationships to other taxa in the genus are also discussed, and the new combination X. rutherfordii (Mart. Rodr., P. Vargas, M. Carine & Jury) Mart. Rodr. & M. B. Crespo comb. nov. is provided.     

A new species, Herbertia crosae (Iridaceae), from Uruguay

Herbertia crosae (Iridaceae) is described from the stony grasslands of northwestern Uruguay. The new species resemblesHerbertia lahue but can be easily distinguished by the narrower leaves, slender habit, the smaller pale lilac flowers, the presence of yellow spots at the base of the tepals, the red, adpressed hairs along the filament column, the presence of filaments free at the apex, the channeled style arm, the recurved secondary divisions of the style arm, and the smaller fruits. A key to the species of the genus is provided in which five species are now recognized.     

Iris celikii (Iridaceae), a new species from north-eastern Turkey

Iris celikii occurring in NE Turkey is described as a species new to science and illustrated. Its ecology, distribution and taxonomic relationships are discussed.     

Tigridia amatlanensis (Tigridieae: Iridaceae), a new species from Oaxaca, Mexico

Tigridia amatlanensis is described and illustrated as a new species from Mexico. It is recognized by its nodding flowers and its inner and outer tepals cirrhous and markedly dimorphic in length. It is most closely related toT. hallbergii subsp.hallbergii andT. meleagris. Other morphologically similar species areT. catarinensis andT. molseediana.     

The species of Geissorhiza (Iridaceae) of Thunberg's herbarium (Uppsala, Sweden)

The complex typification and nomenclature of the eight species of Geissorhiza based on Thunberg's Cape collections, is reviewed critically in preparation for a complete revision of the genus. These species, initially assigned to Ixia , were described by Thunberg and von Linné fil., founded on collections of twelve different species. Some well known species require changes to their nomenclature; G. rochensis sensu Ker becomes G. radians (Thunb.) Goldbl.; while Ixia scillaris Thunb. nom. illeg., based on three different species is lectotypified and shown to be G. scillaris Spreng., a species quite distinct from G. juncea , with which it has often been confused. Arguments for considering the name G. secunda illegitimate are reviewed. The species long known by this epithet must be called G. aspera Goldbl. Lectotypes have been designated for G. monanthos, G. radians, G. scillaris and G. setacea , none of which have been satisfactorily typified before.     

Crocus sativus and its allies (Iridaceae)

Crocus sativus is an autumn-flowering species, unknown as a wild plant but long-cultivated for its scarlet style branches which yield Saffron, the dye and flavouring agent. There are several naturally-occurring related species from southern Europe and south western Asia which form a natural group within the genus.C. niveus from Greece is similar to these morphologically and is included here but is less closely related. The characters of the group are defined, a key to the taxa is provided and their relationships discussed.     

A new species of Herbertia (Iridaceae) from SE South America

A new species of Herbertia , of the Iridaceae, viz. H. quareimana sp. nov, is described; the species is found in the region of the Quareim river, on both sides of the border between Brazil and Uruguay. A key to the species of the genus is provided.     

Cytogenetic studies of cultivatedCrocus sativus (Iridaceae)

Meiosis and mitosis are described in cultivatedCrocus sativus of Iran. This indicates that this species is an autotriploid and sterile. Karyotype analysis, rare inversions, laggard chromosomes and distribution of chromosomes in the first anaphase are described, and the reasons for its sterility are given.