Pollination and Breeding System of Putoria calabrica (Rubiaceae), a Mediterranean Dwarf Shrub

Abstract

The pollinator spectrum and the reproductive system of Putoria calabrica, a Mediterranean chamaephyte, were studied. Its flowers are markedly protandrous and the situation of the style with respect to the stamens can be described as approach herkogamy. In the male phase, the 4 lobes of the corolla are completely extended, but in the female, they are curved back, significantly decreasing the size of the corolla. The volume and sugar content of the nectar were similar between phases, with the concentration being slightly higher in the female phase (41.9 % versus 34.5 %). Putoria calabrica is totally self-compatible; the pollen, both the plant's own and from outside, emitted pollen tubes that reached the ovules within 48 h, and the percentages of fruit set from both types of pollination were high and similar. Diurnal and nocturnal pollinators originated 48.95 % and 15.2 % of fruit set, respectively, while fruit set from free pollination was similar to the sum of the former two. Diptera (mainly Bombyliidae) and Lepidoptera were the most important pollinators, visiting a high number of flowers per plant. The role of protandry and morphological changes of the corolla of Putoria calabrica in its reproductive success are discussed.

Putoria - Rubiaceae - Mediterranean - protandry - pollination

References

• 01 Andersson,  S.. (1996);  Floral display and pollination success in Senecio jacobaea (Asteraceae): Interactive effects of head and corymb size.  Amer. J. Bot.. 83 71-75
• 02 Bahadur,  B.. (1968);  Heterostyly in the Rubiaceae: A review.  Journal of Osmania University (Science),. Golden Jubilee Special Volume 207-238
• 03 Bawa,  K. S., and Beach,  J. H.. (1983);  Self-incompatibility systems in the Rubiaceae of a tropical lowland wet forest.  Amer. J. Bot.. 70 1281-1288
• 04 Bawa,  K. S., and Opler,  P. A.. (1975);  Dioecism in tropical forest trees.  Evolution. 29 167-179
• 05 Bawa,  K. S., and Opler,  P. A.. (1977);  Spatial relationships between staminate and pistillate plants of dioecious tropical forest trees.  Evolution. 31 64-68
• 06 Bertin,  R. I., and Newman,  C. M.. (1993);  Dichogamy in angiosperms.  Bot. Rev.. 59 112-152
• 07 Bremekamp,  C. E. B. (1966);  Remarks on the position, the delimitation and the subdivision of the Rubiaceae.  Acta Bot. Neerlandica. 15 1-33
• 08 Cruden,  R. W., and Herman,  S. M.. (1983) Studying nectar? Some observations on the art. The Biology of Nectaries. Bentley, B. and Elias, T., eds. New York; Columbia University Press pp. 217-237
• 09 Delph,  L. F.. (1996) Flower size dimorphism in plants with unisexual flowers. Floral Biology. Lloyd, D. G. and Barret, S. C. H., eds. New York; Chapman and Hall pp. 217-237
• 10 Faegri,  K., van der Pijl,  L.. (1979) The Principles of Pollination Ecology. Oxford; Pergamon Press
• 11 Ganders,  F. R.. (1975);  Fecundity in distylous and self-incompatible homostylous plants of Mitchella repens (Rubiaceae).  Evolution. 29 186-188
• 12 Garnock-Jones,  P. J., and Malloy,  B. P.. (1982);  Protandry and inbreeding depression in Hebe amplexicaulis (Scrophulariaceae).  New Zealand J. Bot.. 20 401-404
• 13 Imbert,  F. M., and Richards,  J. H.. (1993);  Protandry, incompatibility, and secondary pollen presentation in Cephalanthus occidentalis (Rubiaceae).  Amer. J. Bot.. 80 395-404
• 14 Levin,  D. A.. (1974);  Spatial segregation of pins and thrums in populations of Hedyotis nigricans. .  Evolution. 28 648-655
• 15 Lloyd,  D. G., and Webb,  C. J.. (1986);  The avoidance of interference between the presentation of pollen and stigmas in angiosperms. I. Dichogamy.  New Zealand Journal of Botany. 24 135-162
• 16 Lloyd,  D. G., and Webb,  C. J.. (1992) The evolution of heterostyly. Evolution and Function of Heterostyly. Barret, S. C. H., ed. Berlin; Springer-Verlag pp. 149-178
• 17 Martin,  F. W.. (1959);  Staining and observing pollen tubes in the style by means of fluorescence.  Stain Technol.. 34 125-128
• 18 Murray,  B. G.. (1990);  Heterostyly and pollen-tube interactions in Luculia gratissima (Rubiaceae).  Annals of Botany. 65 691-698
• 19 Nilsson,  L. A.,, Rabakonandrianina,  E.,, Pettersson,  B.,, and Ranaivo,  J.. (1990);  “Oxoroid” secondary pollen presentation and pollination by small moths in the Malagasy treelet Ixora plathythyrsa (Rubiaceae).  Plant Syst. Evol.. 170 161-175
• 20 Ortiz,  P. L.,, Arista,  M.,, and Talavera,  S.. (1996);  Producción de néctar y frecuencia de polinizadores en Ceratonia siliqua L. (Caesalpiniaceae).  Anales del Jardín Botánico de Madrid. 54 540-546
• 21 Pailler,  T., and Thompson,  J. D.. (1997);  Distyly and variation in heteromorphic incompatibility in Gaertnera vaginata (Rubiaceae) endemic to La Reunion Island.  Amer. J. Bot.. 84 315-327
• 22 Richards,  J. H., and Koptur,  S.. (1993);  Floral variation and distyly in Guettarda scabra L. (Rubiaceae).  Amer. J. Bot.. 80 31-40
• 23 Robbrecht,  E.. (1988);  Tropical woody Rubiaceae.  Opera Bot. Belg.. 1 1-271
• 24 Sobrevila,  C.,, Ramírez,  N.,, and De Enrech,  N. X.. (1983);  Reproductive biology of Palicourea fendleri and P. petiolaris (Rubiaceae), heterostylous shrubs of a tropical cloud forest in Venezuela.  Biotropica. 15 161-169
• 25 Stanton,  M. L.,, Snow,  A. A.,, and Handel,  S. N.. (1986);  Floral evolution: attractiveness to pollinators increases male fitness.  Science. 232 1625-1627
• 26 Stone,  J L.. (1995);  Pollen donation patterns in a tropical distylous shrub (Psychotria suerrensis; Rubiaceae).  Amer. J. Bot.. 82 1390-1398
• 27 Stone,  J L.. (1996);  Components of pollination effectiveness in Psychotria suerrensis, a tropical distylous shrub.  Oecologia. 107 504-512
• 28 Takhtajan,  A.. (1996) Diversity and classification of flowering plants. New York; Columbia University Press
• 29 Valdés,  B.,, Talavera,  S.,, and Fernández-Galiano,  E.. (1987) Flora Vascular de Andalucía Occidental. Tomo 2. Barcelona; Ketres
• 30 Verdcourt,  B.. (1958);  Remarks on the classification of the Rubiaceae.  Bulletin de Jardin Botanique de l'Etat, Bruxelles.. 28 209-314
• 31 Webb,  C. J., and Lloyd,  D. G.. (1986);  The avoidance of interference between the presentation of pollen and stigmas in angiosperms. II. Herkogamy.  New Zealand J. Bot.. 24 163-178
• 32 Willson,  M. F.. (1983) Plant reproductive ecology. New York; John Wiley and Sons
• 33 Wyatt,  R., and Hellwig,  R. L.. (1979);  Factors determining fruit set in heterostylous bluets, Houstonia caerulea (Rubiaceae).  Systematic Botany. 4 103-114
• 34 Yeo,  P. F.. (1993);  Secondary pollen presentation. Form, function and evolution.  Plant Syst. Evol. Suppl.. 6 1-268
• 35 Zapata,  T. R., and Arroyo,  M. T. K.. (1978);  Plant reproductive ecology of a secondary decidous tropical forest in Venezuela.  Biotropica. 10 221-230

Section Editor: G. Gottsberger