| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
2Instituto Multidisciplinario de Biología Vegetal, C. C. 495, 5000 Córdoba, Argentina; 3Department of Ecology and Evolutionary Biology, Storrs, Connecticut 06269-3043; 5Casilla 1340, Concepción, Chile; 6Institüt für Botanik, Universität Wien, Rennweg 14, A-1030, Vienna, Austria; 7Department of Plant Biology, Ohio State University, Columbus, Ohio 43210
Lactoris fernandeziana, monotypic in its family, is endemic to the cloud forests of Robinson Crusoe Island. Although there has been considerable study of the relationships of Lactoris, as a rare species and as a putative primitive paleoherb, little is known of its reproductive biology. Knowledge of the latter is essential for effective conservation programs. The species is gynomonoecious. The overall proportion of flowers is 
1 female:1 hermaphrodite. The inconspicuous semipendulous green flowers, usually in mixed-gender inflorescences, do not produce rewards. Hermaphrodite flowers are herkogamous and protogynous. Pollen grains are shed from the extrorse anthers in permanent dry tetrads. There is a mean of 12879 tetrads per hermaphrodite flower. Both flower types bear an average of 18 ovules. The P/O (pollen/ovule) ratios imply facultative or obligate xenogamy, but hand pollinations show that Lactoris is self-compatible. No floral visitors were ever observed, but stigmata of open-pollinated flowers bore tetrads, and 64% of such styles had pollen tubes. Flowers enclosed in large mesh (1 mm) bags bore similar numbers of tetrads and pollen tubes. Thus, we conclude that Lactoris is anemophilous, a syndrome perhaps reflected by the P/O ratio. Low genetic diversity (isozymes and DNA) supports selfing and implies limited distance wind pollen dispersal. The small size of the island, the ± 1000 extant Lactoris plants, coupled with anemophily, self-compatibility, and pendant flower position, have yielded a geitonogamous system with high seed set and low genetic diversity. If inbreeding depression is expressed, it is in seed germination and seedling vigor, for Lactoris is very difficult to cultivate. For this species, effective conservation practices need to focus on habitat preservation and promotion of outcrossing.
Key Words: basal angiosperms • conservation biology • island biology • Lactoridaceae • monoecy • reproductive biology • self-compatibility • wind pollination
This article has been cited by other articles:
|
|
 |
|
  S. Y. Smith and R. A. Stockey Establishing a fossil record for the perianthless Piperales: Saururus tuckerae sp. nov. (Saururaceae) from the Middle Eocene Princeton Chert Am. J. Botany, October 1, 2007; 94(10): 1642 - 1657. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. ROSSELLO and M. MAYOL Seed Germination and Reproductive Features of Lysimachia minoricensis (Primulaceae), a Wild-extinct Plant Ann. Bot., May 1, 2002; 89(5): 559 - 562. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Gonzalez and P. Rudall The questionable affinities of Lactoris: evidence from branching pattern, inflorescence morphology, and stipule development Am. J. Botany, December 1, 2001; 88(12): 2143 - 2150. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. J. Crawford, E. Ruiz, T. F. Stuessy, E. Tepe, P. Aqeveque, F. Gonzalez, R. J. Jensen, G. J. Anderson, G. Bernardello, C. M. Baeza, et al. Allozyme diversity in endemic flowering plant species of the Juan Fernandez Archipelago, Chile: ecological and historical factors with implications for conservation Am. J. Botany, December 1, 2001; 88(12): 2195 - 2203. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. J. Anderson, G. Bernardello, T. F. Stuessy, and D. J. Crawford Breeding System and pollination of selected plants endemic to Juan Fernandez Islands Am. J. Botany, February 1, 2001; 88(2): 220 - 233. [Abstract] [Full Text]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
