The reproductive phenology of three mistletoe species in the Loskop Dam Nature Reserve, South Africa

In order to gain a clearer understanding of the mistletoe fruit/avian disperser interacting system the flowering and fruiting phenologies of Tapinanthus leendertziae (Sprague) Wiens. T. natalitius ssp zeyheri (Harv.) Wiens, and Viscum combreticola Engl. were studied in the Loskop Dam Nature Reserve. South Africa. Both Tapinanthus species produced flowers and fruit seasonally but followed quite different patterns. T. natalitius showed rapid flower production but subsequently slow fruit production, resulting in a low number of ripe fruit simultaneously available on a plant. T. leendertziae showed a slower flower production followed by a quick mass production of fruit. The peaks of the different phonological stages tended to be separate in T. natalitius but overlapped greatly in T. leendertziae. In the latter species peak flower production was reached later than in T. natalitius, but peak fruit production earlier, presumably resulting in less competition for pollinating and dispersal agents. Open, nectar-producing flowers were available for 12 weeks in T. natalitius compared with 21 weeks in T. leendertziae; a total period of Tapinanthus nectar availability of 22 weeks. Ripe fruits were available for 11 weeks in T. leendertziae compared with 20 weeks in T. natalitius; a total period of Tapinanthus fruit availability of 26 weeks. The mean period of the whole reproductive cycle in individual plants was 22 weeks in T. leendertziae compared with 40 weeks in T. natalitius. Viscum combreticola differed completely from both Tapinanthus species, producing flowers and fruit throughout the year. In ’n poging om meer duidelikheid te verkry oor die voëlentvrug/voël- verspreider interaksiesisteem, is die blom- en vrugfenologie van Tapinanthus leendertziae (Sprague) Wiens. T. natalitius ssp zeyheri (Harv.) Wiens en Viscum combreticola Engl. in die Loskopdam- natuurreservaat. Suid-Afrika, bestudeer. Albei Tapinanthus-spesies pro- duseer blomme en vrugte seisoenaal maar volg verskillende patrone. T. natalitius het ’n vinnige blomproduksie getoon, gevolg deur ’n stadige produksie van vrugte, wat ’n lae getal vrugte gelyktydig beskikbaar op n plant tot gevolg gehad het. In T. leendertziae was blomproduksie stadig, gevolg deur ’n vinnige massaproduksie van vrugte. Die pieke van die verskillende fenologiese stadia was geskei in T. natalitius maar in T. leendertziae het hulle grootliks oorvleuel. In laasgenoemde spesie is die piek van blomproduksie later bereik as in T. natalitius maar die piek van vrugproduksie vroeër. Dit het waar- skynlik minder kompetisie vir bestuiwings- en verspreidingsagente tot gevolg gehad. Oop. nektar-produserende blomme was vir 12 weke beskikbaar in T. natalitius vergeleke met 21 weke in T. leendertziae; ’n totale tydperk van beskikbaarheid van Tapinanthus-nektar van 22 weke. Ryp vrugte was vir 11 weke in T. leendertziae beskikbaar vergeleke met 20 weke in T. natalitius; ’n totale tydperk van beskikbaarheid van Tapinanthus-vrugte van 26 weke. Die gemiddelde tydperk van die hele voortplantingsiklus in individuele plante was 22 weke in T. leendertziae vergeleke met 40 weke In T. natalitius. Viscum combreticola het geheel en al van albei Tapinanthus-spesies verskil deur blomme en vrugte dwarsdeur die jaar voort te bring.