Karyomorphological studies onWoodwardia sensu lato of Japan

Karyomorphological comparisons were made of five species of JapaneseWoodwardia. There were no marked differences at interphase and prophase among the five species.Woodwardia japonica, W. prolifera, andW. unigemmata were diploid with 2n=68 and the formulas of their metaphase karyotypes uniformly 4m(median centromeric chromosomes)+12sm(submedian)+52(st+t)(subterminal and terminal).Woodwardia orientalis was tetraploid with 2n=136 and 8m+24sm+104(st+t), and the ratio of each chromosomal type to total complement was identical to that of three diploid species. These four species had several characteristics in common:x=34, the longest chromosome of sm, and a mean chromosome length over 3.0 μm. AlthoughWoodwardia orientalis showed some similarity toW. prolifera, it seems to be an allotetraploid which originated by chromosome doubling of a hybrid ofW. prolifera and a diploid species as yet karyomorphologically unknown.Woodwardia kempii was tetraploid with 2n=124 and 8m+24sm+92(st+t), and differed from the others in havingx=31, the longest chromosomes of t, and a mean chromosome length under 3.0 μm. This species has been classified as an independent genus,Chieniopteris, and our karyomorphological study supports this treatment.     

The structure and development of the haustorium in parasitic Scrophulariaceae*

The structure and development of roots and haustoria in 37 species of parasitic Scrophulariaceae was studied using light microscopy. The mature haustorium consists of two regions: the swollen “body” and the parent root, which resembles non-haustorial roots in structure. The body arises from the parent root and is composed of an epidermis, cortex, central region of xylem (the vascular core), a region of parenchyma (the central parenchymatous core), and the portion of the haustorium contained in the host tissue (the endophyte). The xylem of the vascular core is composed predominately of vessel elements. The central parenchymatous core is composed of parenchyma and col-lenchyma. Vessels extend from the vascular core through the central parenchymatous core to the endophyte. The endophyte is composed of parenchyma cells and vessel elements. No phloem is present in the body of the haustorium. Early stages in the development of the haustorium are exogenous. Initial periclinal divisions in the epidermis or outer cortex are followed by hypertrophy of cortical parenchyma. These events are followed by development of the vascular core from the pericycle, attachment of haustorium to the host by a specialized layer of cementing cells or root hairs, and penetration of the host by dissolution of host cells.     

Epicuticular flavonoids of some Scrophulariaceae

Twenty-two species of Scophulariaceae have been found to accumulate flavonoid aglycones externally on their leaves and stems. They belong to the genera Anarrhinum, Antirrhinum, Asarina, Calceolaria, Mimulus, and Odontites. Most of the flavonoids are methylated flavones and flavonols, some with 6-O and/or 8-O-substitution. One of them is the natural isobutyryl ester of a rare flavone.     

Karyomorphological studies of theIxeris dentata complex on Mount Ishizuchi

The karyotypes of four taxa in theIxeris dentata complex collected from Mt. Ishizuchi were investigated.I. dentata subsp.dentata var.dentata f.dentata had 2n=21 in all the examined individuals and its karyotypes were classified into four different types. Var.dentata f.amplifolia showed 2n=21 in all individuals and had three different karyotypes.I. dentata subsp.dentata var.albiflora showed 2n=21 and two different karyotypes.I. dentata subsp.alpicola showed three different karyotypes with 2n=21 and four different ones with 2n=28. Judging from the results of the karyotype analyses, the morphological variation of chromosomes in theI. dentata complex is assumed to be in the process of increasing asymmetry in the shape of chromosomes. Following Levitzky's principle, it can be said that the a-, b-, and c-chromosomes exist in different advanced stages in the process of chromosome variation. The c-group chromosomes are at the most advanced stage in morphological variation, the b-group in the second and the a-group in the least advanced stage. The above-mentioned structural diversity of chromosomes may be related to apomictic reproduction of theI. dentata complex.     

Pollen morphology and infra-generic evolutionary relationships in some Chinese species of Pedicularis (Scrophulariaceae)

 The pollen grains of 32 Chinese species of Pedicularis representing 13 groups within the genus were investigated using light microscopy and scanning electron microscopy. The genus is eurypalynous, the apertures may be tricolpate, trisyncolpate, or bisyncolpate and five types of surface ornamentation (microscabrate, microrugulate, retipilate, microreticulate and microfoveolate) were observed. Comparison of the different aperture types using light microscopy allows three pollen types to be distinguished. Examination of exine ornamentation with scanning electron microscopy enabled each pollen type to be divided into two or three sub-types (giving a total of seven sub-types). Pollen morphology within the genus is discussed in relation to infrageneric relationships, evolutionary and pollination biology. There is little correlation with the existing infrageneric taxonomy (some taxonomic groups have more than one pollen type, while the same pollen type may be found in several different species-groups), but greater correlation with the corolla morphology. Received January 10, 2002; accepted March 5, 2002 Published online: March 10, 2003     

Cytological studies in some species of Momordica

In the genus Momordica three species M. charantia, M. balsamina and M. dioica, have been cytologically investigated. M. dioica has a more asymmetrical karyotype than the other two species.Meiosis in the three species is regular. The strictly monoecious M. charantia and M. balsamina show similarity in the range and frequency of bivalents and chiasmata, whereas M. dioica, a dioecious species, has fewer half chiasmata per chromosome. The evolutionary significance of perennial and annual habits along with allogamous and autogamous breeding systems is discussed. The incompatibility between 2n=22 and 2n=28 species in this genus is strongly indicated by the negative results of crossings between M. charantia and M. balsamina on one side and M. dioica on the other. The possible origin of M. dioica from M. charantia is discussed.This research has been financed in part by a grant made by the United States Department of Agriculture under PL 480.     

Population structure, genetic diversity and host specificity of the parasitic weedStriga hermonthica (Scrophulariaceae) in Sahel

Seed proteins of individual plants from 14 populations ofStriga hermonthica growing on sorghum, millet, maize and wild grasses in Burkina Faso, Mali and Niger were studied using gel electrophoresis in order to assess the population structure and genetic diversity of the parasitic weed. The relative intensity of the different bands within a pattern was used to depict the genotypic constitution of each sample. Genotypic frequencies conformed to Hardy-Weinberg expectations in 13 populations out of 14 for the two loci that were interpreted. Heterozygote deficiencies could be the result of the Wahlund effect. The genetic divergence between populations appears to be low for bothAdh andGot loci. Thus, the physiological specialization for a particular host could be a recent phenomenon. A low host specificity ofS. hermonthica populations could affect the efficiency of introducing new resistant cultivars as a control measure against the parasitic weed.     

Karyological studies of some species of the Mongolian flora

The paper gives the chromosome numbers for 38 species of the Mongolian Flora. Some of the counts appear to be the first findings for the species. They are:Allium anisopodium 2n = 16, Caltha membranacea 2n = 32, Carex macroura 2n = 50, Carex redowskiana 2n = 26, Gastrolychnis brachypetala 2n = 72, Iris biglumis 2n = 40, Iris flavissima 2n = 28 andVicia multicaulis 2n = 24.     

Cytological studies on some species in genus Pennisetum

Summary Detailed microsporogenesis in 4 species of the genus Pennisetum namely P. typhoides (n = 7), P. longistylum (n = 18), P. polystachyon (n = 27) and P. pedicellatum (n = 27) was studied. Nature of chromosome pairing was critically studied and pairing was regular in diploid and allotetraploid species. Some multivalents formation occurred in segmental allopolyploids. They displayed numerous meiotic irregularities. Aberrant meiosis in the material is evaluated. The role of apomixis, hybridization and polyploidy in the evolution of the genus is discussed.

---

Zusammenfassung Es wird über eingehende Untersuchungen der Mikrosporogenese in 4 Species der Gattung Pennisetum, nämlich P. typhoides (n = 7), P. longistylum (n = 18), P. polystachyon (n = 27) und P. pedicellatum (n = 27) berichtet. Die Art der Chromosomenpaarung wurde kritisch geprüft, sie war bei den diploiden und allotetraploiden Species regulär. Multivalentbildung trat in einigen Fällen bei Segment-Allopolyploiden auf, sie zeigten zahlreiche meiotische Unregelmäßigkeiten. In dem Material aufgetretene aberrante Meiosen wurden ausgewertet. Die Rolle von Apomixis, Hybridisation und Polyploidie bei der Evolution der Gattung wird besprochen.

     

Cyto-morphological studies op some species and hybrids in the Eu-Sorghums

Summary Important morphological features such as plant height, leaf size and number of leaves, shape of the panicle and sessile spikelets, staminate condition of the pedicellate florets, nature of lemma, colour of the stigmatic surface and seeds etc., were studied in 8 Sorghum species and 10 F₁ hybrids between them. Based on the data, interrelationship amongst the species are discussed.Pachytene pairing was complete and apparently normal, followed by regular meiosis at later stages resulting in high pollen stainability and good seed setting in all the parental species except the male sterile Kafir. Studies on the pairing properties of the differentially stained regions showed that synapsis starts from the proximal to the distal end and separation of the split chromosomes starts from the distal to the proximal.The interspecific hybrids studied are classified into four types based on pachytene pairing and pollen sterility. 1. normal pairing accompanied by high pollen fertility, 2. normal pairing accompanied by partial pollen sterility. 3. irregularities in the pachytene pairing followed by partial pollen sterility and 4. irregularities in the pachytene pairing accompanied by normal pollen fertility. Suitable explanations are advanced to explain the meiotic aberrations noted in some of the hybrids under study.Cytogenetical mechanisms underlying species differentiation in the Eu-Sorghum species are discussed.     

Nomenclatural changes in some intermountain penstemons (Scrophulariaceae)

Fifteen new combinations and one new binomial inPenstemon, to be used in a floristic treatment of the genus in theIntermountain Flora, are published herewith.     

A species-specific recognition system directs haustorium development in the parasitic plant Triphysaria (Scrophulariaceae)

Parasitic plants use host molecules to trigger developmental programs essential for parasitism. One such program governs the initiation, development, and function of haustoria, parasite-specific organs responsible for attachment and invasion of host tissues. Haustoria development can be initiated by several different molecules produced by appropriate host species. We are interested in understanding how these signals are interpreted by two related facultative parasites, Triphysaria eriantha (Benth.) Chuang and Heckard, and T. versicolor Fischer and C. Meyer, to distinguish their own roots from those of potential hosts. We used an in vitro bioassay to determine what proportion of different Triphysaria populations formed haustoria in the presence and absence of closely related and unrelated host species. We found that the proportion of plants with haustoria was the same whether the plants were grown in isolation or with a conspecific host. In contrast, a significantly higher proportion of plants made haustoria when the host was a congeneric Triphysaria. Plants with haustoria neither enhanced nor inhibited other plants' propensity to form haustoria. Together these results indicate that qualitative differences exist in haustorium-inducing factors exuded by closely related species. The highest proportion of Triphysaria had haustoria when grown with Arabidopsis thaliana (L.) Heynh. Even in this case, however, some Triphysaria failed to develop haustoria. Interestingly, the percentage of haustoria that had vessel elements was higher when connections were made with Arabidopsis than with another Triphysaria. These results demonstrate that host recognition can be manifested at multiple points in haustorium development. Received: 18 December 1996 / Accepted: 14 February 1997     

A new species of Misopates Raf. (Scrophulariaceae, Antirrhineae)

Misopates pontiense sp. nov. is described from one population located in the north-west of the Iberian Peninsula. It is an annual, living on charred soils. Its distinguishing characteristics include its seeds, which have a carinate dorsal face and an encircling rounded ridge with cylindrical papillae, but lack a median ridge on the ventral face. Morphological characters and taxonomic affinities are discussed.     

Occurrences of degeneration in some parasitic dermatophytes

Summary In single hairs taken from the trichophytosis like areas of infection ofMicrosporon audouinii, which was found in the lethal stage of theMicrosporon-endemic, the author could observe a rudimentary spore-production and deformation due to degeneration. He could find similar changes on fungous hyphae in hairs, which have been infected byArthroderma asteroides. Signs of a similar disintegration — which were, however, of different character — could be observed on the filaments of fungi in the lamellae of trichophytosis, caused byTrichophyton felineum. In the author's opinion these changes are to be regarded as consequences of the degradation taking place in fungous strains.     

Nutritional studies of Hemiparasitic Orthocarpus (Scrophulariaceae)

Excised shoot tips from Orthocarpus attenautus and O. purpurascenswere cultured in vitro to ascertain whether the stem tips ofthese hemiparasites require complex organic substances for theirdevelopment, and to determine if the capacity for haustoriaformation is retained by the resulting plantlets. Explants consistedof the apical meristem plus the four smallest leaf primordia,having a volume of less than 0.5 mm3. A variety of mineral media,sucrose concentrations, root extract, soil extract, yeast extract,and malt extract were tested for effects on growth. Both speciescompleted development in sterile culture on simple media. Orthocarpusattenuatus grew best on Knop‘s minerals with Ball’smicroelements + 0.1 g ferric citrate 1–1+ 1% (w/v) sucrose,while MurashigeSkoog‘s minerals+ 2% sucrose provided thebest growth of the media tested for O. purpurascens. Haustoriaformed on the roots of all plantlets chemically induced by cottonstring. The mean number of haustoria per plantlet was abouthalf that of control plants raised from seed. Growth of intactO. Purpurascens seedlings was also compared on mineral agar,mineral agar supplemented with yeast extract, and in soil culturessupplemented with yeast extract and a host. While yeast extracthas variable effects on the growth of shoot tip explants andintact plants raised under axenic conditions, it is highly stimulatoryto the autotrophic growth of intact plants in soil culture.     

Reproductive strategies in two arctic Pedicularis species (Scrophulariaceae)

A study of a number of reproductive traits in two sympatric species of Pedicularis in northern Swedish Lapland, the subarctic-alpine P lapponica and the artic P hursuta , revealed that the life-history strategies of the two species differ profoundly High fruit set and low seed abortion rate, as m P hursuta , is common in arctic plants in late-thawing habitats and represents a case of extreme adversity selection rather than an indication of a ruderal life-history strategy Pedicularis lapponica , on the other hand, is a typical K-strategist (or stress-tolerator) requiring a longer period of growth for optimal reproduction Occuring at both low and high altitudes in the area, P lapponica tends to increase in self-compatibility with altitude, which is interpreted as an adaptation to lower pollinator visitation frequency in arctic environments The variation in length of the protruding part of the style in P lapponica is shown to be correlated with exposure to light Predispersal seed predation is severe m P lapponica at low altitudes, where the capsules are attacked by fly and moth larvae At high altitudes, a minor proportion of the capsules of P lapponica experience predation and only from flies, while P hursuta is completely unpredated