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Mating among closely-related individuals in small and isolated plant populations may result in reduced vigour of the inbred offspring, i.e. inbreeding depression, especially in naturally outbreeding plants. Occurrence of inbreeding and inbreeding depression was studied in Saintpaulia ionantha ssp. grotei, a threatened endemic plant species with a narrow ecological amplitude from the East Usambara Mountains. The level of inbreeding (measured as the fixation index, F) was investigated in twelve populations by analyzing variation at one microsatellite marker locus. The effect of one generation of selfing and outcrossing on the progeny fitness was studied by controlled crosses in two small patches that differ in the level isolation. The fixation index (F) across the populations was on the average 0.21 and varied among the populations from substantial inbreeding (F = 0.58) to surplus heterozygosity (F = −0.29). High inbreeding depression (δ) was observed at early and late stages of the life-cycle. The isolated patch exhibited lower inbreeding depression than did the non-isolated patch. The results of this study suggest that inbreeding and subsequent inbreeding depression are potential threats to the survival of Saintpaulia populations. Resume L’accouplement d’individus etroitement lies, dans des petites populations vegetales isolees, peut aboutir a une vigueur moindre de la progeniture de meme souche, c’est-a-dire une depression due a l’endogamie, specialement chez des plantes qui sont naturellement exogames. L’occurrence de l’endogamie et de la depression qui y est liee a eteetudiee chez le Saintpaulia ionantha spp. grotei, une plante endemique menacee qui n’a qu’une faible amplitude ecologique dans l’est des Usambara Mountains. On a recherche le taux d’endogamie (mesure par l’indice de fixation F) dans 12 populations en analysant la variation d’un locus microsatellite marqueur. L’effet d’une generation d’auto- et d’allofecondation sur l’aptitude (fitness) de la progeniture a eteetudie par des croisements controles dans deux petites parcelles dont le degre d’isolement differait. L’indice de fixation F dans les populations etait en moyenne de 0,21 et il variait d’une autofecondation substantielle (F = 0,58) a une heterozygosite en surplus (F = −0,29). Une forte depression due a l’endogamie (δ) a ete observee aux stades precoce et tardif du cycle vital. La parcelle isolee a presente une depression liee a l’endogamie moins forte que celle de la parcelle non isolee. Les resultats de cette etude suggerent que l’auto-fecondation et la depression qui en resulte sont des menaces potentielles pour la survie des populations de Saintpaulia.

Knowledge of the reproductive biology of endangered plants is essential for their effective conservation. It also provides important information for understanding the evolutionary processes that affect speciation, thus helping the definition of proper units for conservation in endangered plants with problematic taxonomy. We studied the reproductive potential and possibility for hybridization in the endangered genus Saintpaulia (Gesneriaceae) by examining flowering phenology, flower and seed production and pollination of three sympatric cross-compatible Saintpaulia species in the East Usambara Mts., Tanzania. The synchrony observed in flowering in S. confusa and S. difficilis may enable hybridization between these two species, whereas partial phenological separation may contribute to the integrity of S. grotei. Although the level of flower abortion is high in S. confusa, each pollinated flower yields about 1000 seeds. Saintpaulia confusa produces fruits following both self- and cross-pollination but spontaneous self-pollination seems not to occur. Thus, seed production depends on sufficient pollinator service. Floral heteromorphy (i.e. enantiostyly) and bee pollination are likely to further enhance cross-pollination, suggesting that the genus predominantly outcrosses. Thus, Saintpaulia populations are likely to suffer from negative effects of inbreeding if they become small and isolated. Resume La connaissance de la biologie de la reproduction des plantes en danger est essentielle pour l'efficacite de leur conservation. Elle fournit aussi des informations importantes pour la comprehension des processus evolutifs qui touchent la speciation et donc pour la definition d'unites adequates pour la conservation de plantes en danger dont la taxonomie pose des problemes. Nous avons etudie le potentiel reproductif et la possibilite d'hybridation du genre menaceSaintpaulia (Gesneriaceae) en examinant la phenologie de la floraison, la production de fleurs et de semences, et la pollinisation de trois especes de Sainpaulia sympatriques de l'est des Usambara Mountains, en Tanzanie, qui peuvent se croiser. La synchronie de la floraison observee avec S. confusa et S. difficilis permet peut-etre l'hybridation entre ces deux especes, tandis qu'une separation phenologique partielle pourrait contribuer a conserver l'integrite de S. grotei. Meme si le niveau d'avortement est eleve pour les fleurs de S. confusa, chaque fleur fecondee produit environ 1000 semences. S. confusa produit des fruits apres la pollinisation par sa propre espece ou par croisement avec une autre espece, mais il semble qu'il n'y ait pas d'auto-pollinisation spontanee. Donc, la production de semences depend de l'abondance des pollinisateurs. L'heteromorphie florale (i.e. enantiomorphisme) et la pollinisation par les abeilles sont susceptibles de stimuler la pollinisation croisee, ce qui suggere que ce genre se reproduit surtout de cette facon. Il est donc probable que les populations de Saintpaulia risquent de souffrir des effets negatifs de l’inbreeding si elles deviennent trop petites et isolees.

Summary. Two new endemic species of Saintpaulia, S. ulugurensis Haston and S. watkinsii Haston (Gesneriaceae) are described from the Uluguru Mountains. Their discovery emphasises the need for additional floristic work to be carried out in this area and supports the calls for strong conservation measures for the fragile forest habitats of Tanzania.

introduction This paper is a preliminary assessment of the conservation status of Saintpaulia H. Wendl. in both the wild and in cultivation. The genus Saintpaulia has been promoted as a botanical ‘panda’ symbolizing the decline of the tropical moist forests, particularly the Eastern Arc mountains of East Africa. In spite of this and it’s familiarity through usage as a house plant there has been no recent review of the conservation needs of the genus. This paper represents an initial attempt to review the status of the genus and makes general recommendations on future conservation activities. The authors have collated and reviewed all the available current information on the genus Saintpaulia from literature, botanic garden databases, and the authors’ own field experience. Using the above information they have assigned an IUCN Category of Threat (IUCN, 1994) to each Saintpaulia species. This initial study highlights the current threats to saintpaulias in the wild, addresses some of the taxonomic problems that are in need of further research and makes recommendations for their conservation. The authors hope that the article will instigate further research, and promote collaboration between conservation organizations, governments and the horticultural industry.

Saintpaulia (Gesneriaceae) is confined in the wild to small patches of forest in East Africa (Tanzania and Kenya), with most of the species occurring in submontane or montane forest. However, a few species are known from lowland forests and this paper outlines the distribution and ecology of some of the species recorded from lowland sites. Additional sites for S. confusa B.L. Burtt, S. diplotricha B.L. Burtt, S. grotei Engl., S. ionantha H. Wendl, S. tongwensis B.L. Burtt and two, possibly new, species, have been located during recent field studies. One of the critically endangered species, S. tongwensis has featured previously in Curtis's Botanical Magazine (N.S. t. 11) and its illustration and description are repeated here.

Phylogenetic relationships of eight species of Saintpaulia H. Wendl., 19 species of Streptocarpus Lindl. (representing all major growth forms within the genus), and two outgroups (Haberlea rhodopensis Friv., Chirita spadiciformis W. T. Wang) were examined using comparative nucleotide sequences from the two internal transcribed spacers (ITS) of nuclear ribosomal DNA. The length of the ITS 1 region ranged from 228 to 249 base pairs (bp) and the ITS 2 region from 196 to 245 bp. Pairwise sequence divergence across both spacers for ingroup and outgroup species ranged from 0 to 29%. Streptocarpus is not monophyletic, and Saintpaulia is nested within Streptocarpus subgenus Streptocarpella. Streptocarpus subgenus Streptocarpus is monophyletic. The ITS sequence data demonstrate that the unifoliate Streptocarpus species form a clade, and are also characterized by a unique 47-bp deletion in ITS 2. The results strongly support the monophyly of (1) Saintpaulia, and (2) Saintpaulia plus the African members of the subgenus Streptocarpella of Streptocarpus. The data suggest the evolution of Saintpaulia from Streptocarpus subgenus Streptocarpella. The differences in flower and vegetative characters are probably due to ecological adaptation leading to a relatively rapid radiation of Saintpaulia.

Of 3272 plants regenerated from protoplasts of 10 Saintpaulia ionantha genotypes, 98.4% survived transfer to the greenhouse. The frequency of regenerants with chlorophyll deficiencies, i.e. variegated leaves or albinos, was low (1.5%). There was a higher number of polyploid, in most cases tetraploid plants, regenerated from protoplasts (16%) which were identified by their altered morphology. Measurements of stomatal length and counting the number of chloroplasts per guard cell also allowed a clear differentiation between diploid and polyploid plants. The classification was confirmed by DNA content determination using flow cytometry. Mechanisms leading to polyploidization included spontaneous protoplast fusion as well as chromosome doubling during callus growth and shoot regeneration. Two genotypes with instabilities in flower colour showed completely altered flower colours in plants regenerated from protoplasts as well as in plants regenerated on leaf explants in vitro.

The results of four experiments on biological control of Frankliniella occidentalis on flowering Saintpaulia ionanfha and one on pelargonium are presented. Three species of predatory mites were used for the experiments: Amblyseius barkeri, and two soil-dwelling species Hypoaspis aculeifer and H. miles. Three releases each of 15 H. miles per saintpaulia plant at weekly intervals did not have any effect on the pest population. In two experiments on saintpaulia, 10 females of H. aculeifer per plant were released weekly for a period of 10 weeks. The increase of thrips population was slowed down for some weeks and population peaks were diminished. However, this treatment failed to keep the pest at a low level. In one experiment, 15 A. barkeri per saintpaulia plant were released weekly for 10 weeks. Thrips population dynamics was slowed down for about 4 weeks, but again the treatment failed to keep the pest at a low level. In one experiment on pelargonium, 15 A. barkeri per plant were released fortnightly for 10 weeks. An effect was obvious in both replicates. Pest populations hardly increased on the plants treated with the biocontrol agent but increased significantly in the controls. The reasons for these results and differences are discussed. The suitability of these three species for production and use as biocontrol agents is discussed.

Plants were grown in chambers with CO2 enrichment (1000 μl 1-1 ) and with or without the addition of 0.85 μl 1-1 nitrogen oxides (NOx ). The following species were tested: Lactuca sativa (lettuce), Cucumis sativus (cucumber), Lycopersicon esculentum (tomato), Saintpaulia ionantha, Rosa, Kalanchoe blossfeldiana, Chrysanthemum×morifolium, Helxine soleirolii, Hedera helix, and Nephrolepis exaltata. All species responded positively to an increase in CO2 level from 330 to 1000 μl 1-1 . The dry weights of tomato, roses and Saintpaulia responded negatively to the addition of NOx . In tomato, the reduced dry weight was due to reduction in shoot length and leaf area. In roses the stem was shorter and in Saintpaulia the leaves smaller when NOx was added. Furthermore, the time to flowering increased and number of flowers/flower buds decreased in Saintpaulia.

The regeneration of buds from leaves of Saintpaulia ionantha Wendl cv. Sona and from cotyledons of Lycopersicon esculentum Mill. cv. UC 105 was studied in response to continuous light and daily light pulses. The regeneration of buds from cotyledons of Lycopersicon esculentum is high under continuous red and white light. Trie effect of light may be related to phytochrome. In Saintpaulia ionantha blue light appears to be very effective. The experimental results suggest that the blue light effects involve both a blue light absorbing photoreceptor and phytochrome

A B S T R A C T Pinwheel flowering African violets are bicolor forms that have a patterned arrangement of colors on the corolla segments. A median band of one color extends radially from the central portion of the corolla on each corolla segment and contrasts with the marginal color. In vitro culture of various tissues was accomplished, and observation of the flowering patterns of the regenerated plants supports the hypothesis that the cultivars 'Valencia', 'Dardevil', and 'Desert Dawn' are periclinal chimeras. Adventitious plants display a high proportion of monochromatic flowers of the same color as the lateral margin of the corolla segments. Petiole cultures from which the epidermal layers were removed yielded plants with flowers of the color of the central stripe of the corolla segments. Pinwheel flowering plants were regenerated through short-term culture of whole inflorescences, suggesting that the African violet inflorescence may possess axillary vegetative meristems. These results support the contention that adventitious shoots may arise from the epidermal layer only (L.I), or with the participation of the epidermal and subjacent layers (L.I and L.II). These results contradict the recent conclusion that all three histogen layers of African violet participate in adventitious shoot organization.

Plants of the foliarly variegated cultivar Saintpaulia ionantha Tommie Lou and the florally variegated cultivar Candy Lou were regenerated through tissue culture from leaf sections, petal sections, and subepidermal tissue. This provided explants with derivatives of all histogen layers of the shoot apex, layers I and II only, and layers II and III only. Over 1,000 plants of Tommie Lou and Candy Lou were grown to flowering. A low level of phenotypic variation was observed, but in no case could this be attributed to the separation of genotypically distinct cell lines. The foliar variegation pattern of both cultivars was stable through in vitro propagation. In contrast, the chimeral components of the flower color pattern in Candy Lou separated during regeneration. These data demonstrate that Tommie Lou-type foliar variegation is not caused by periclinal chimerism and that all leaf cell layers possess the genetic information necessary to produce variegated foliage. The production of all green and all white plants from a radiation-induced periclinal chimera demonstrated that the system used could detect chimeral separation. These results support the contention that adventitious shoots in Saintpaulia almost always differentiate in vitro from a derivative(s) of a single histogen layer, and this layer is usually the LI.

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