KRISTIANSEN, KIM A. Botanical Institute, University of Copenhagen, Gothersgade 140, DK-1123 CPH K, Denmark. - Typical orchid mycorrhiza and protocorm seedling biology found in Neuwiedia.
Orchidaceae subf. Apostasioideae comprises the genera Apostasia
(7 spp.) and Neuwiedia (8 spp.). They are not always included
in Orchidaceae s.str., but are traditionally regarded as
"the most primitive orchids". Recent phylogenetic analyses
of morphological and molecular data place them as sister group to the
remainder of Orchidaceae. Orchids are easily recognized on distinct
floral characters, but several authors have pointed out that
characteristics like the gynostemium, pollinia etc. make sense only in
connection with the unique seedling biology with an obligate
mycotrophic protocorm stage. Protocorms of spontaneous Neuwiedia
veratrifolia seedlings have been found at three locations, and the
mycobiont was subcultivated from live pelotons. The typical orchid
mycorrhizal infection pattern with newly infected cells in the outer
cortex and older degrading pelotons in the inner cortical cells was
observed. The preliminary examination of the fungal endophyte
categorizes it as typical orchid mycorrhiza belonging to the group of
Rhizoctonia-like endophytes.
Key words: Neuwiedia veratrifolia, orchid mycorrhiza, orchid phylogeny, Orchidaceae, protocorm