Monitoring of population of rare orchid Epipogium aphyllum (F.W. Schmidt) Sw. on the isl. Bol’shoj Asaf’ev of Kandalaksha gulf (White sea) have been conducted from 2001 (Kopylov-Gus’kov et al., 2007). Here we present the results of observations made in 10–12 August 2006. We counted generative shoots and flowers on them; we also checked the presence of pollinia in all flowers. We fixed four damaged by animals inflorescences (one flower, two flowers and two inflorescences with three flowers) with 70% ethanol to estimate the potential seed production. Underground parts of several dense groups of generative shoots were thoroughly examined (ground litter was carefully lifted with pincers and then returned). We also made four series of observations on insects, visiting the Epipogium flowers, to reveal possible pollinators. However, the weather was not favorable for flying insects, and we registered only insects, which were not carrying pollinia.
We have found 92 generative shoots (including three, which have lost the flowers) in 2006, what is by 30.8% less than in 2004 (i.e. 133 generative shoots). We think that this level of number of generative shoots decreasing is normal, because we have found only 34 generative shoots in 2001, when we discovered this population (Kopylov-Gus’kov et al., 2007). Note that decreasing of number of the underground shoots does not mean the decreasing of population.
The number of flowers in the inflorescence varied from one (for small individuals) to five, usually 2–3 flowers per inflorescence (30.4 and 37.0% of generative shoots respectively). We registered 216 flowers in total, i.e. 2.4 flowers per inflorescence on average. Nine flowers were damaged, probably by plant-feeder insects (their pollinia were removed traumatically), pollinia were absent in 18 more intact flowers. All these facts suggest that at least small part of plants in the population is insect-pollinated.
Epipogium is known to reproduce both by seeds and by small protocorm-like buds, that develop on the stolons (Irmisch, 1853; Ziegenspeck, 1936). The origin of the individual can not be determined by its appearance. In both cases rhizome has narrow long basal part with rounded tip. However, the individuals with vegetative origin have wide and “succise” basal part, sometimes with uneven margin.
We examined underground organs of four small single generative shoots and four groups, consisting of 2-4 generative shoots each. Underground organs of single shoots were allocated in upper soil layers, in 2.5-5.5 cm below the litter surface (the litter was 2-4 cm thick). Three of four rhizomes had narrow basal tip. This suggests they origin from protocorm or protocorm-like bud. The fourth rhizome had destroyed basal part, which indicates its greater age (at least one year). In the groups of generative shoots only one rhizome gave rise to the two generative shoots. In all the other groups each shoot had its own rhizome, their mutual arrangement and wide margin of basal part suggested their vegetative origin.
We also found eight underground vegetative individuals of different size with unknown origin. They were arranged horizontally, solitary or in small groups. One of the biggest individuals was found closely under the rhizome of small generative shoot. Another one was found between three solitary generative shoots, in 10-30 cm from them. Rhizomes of these big vegetative plants laid in the upper soil layer. Younger underground plants (smaller then 1 cm) were aggregated in two groups of four and two plants in 15–30 cm from the nearest generative shoots. These young plants were situated in the litter of poorly decomposed leaves of woody plants. This suggests these plants being one (or less probable two) years old.
Existence of young plants in mellow thin litter demonstrate that its trampling down is dangerous for the population. We recommend to keep the path-net as modest as possible and, possibly, arrange temporal planked footway during the monitoring of the populations of this rare and mysterious orchid.
We used fixed ovaries for the estimation of potential seed production (see above). We dissected each ovary and put ovules in ethanol-glycerin mixture, arranging them as uniformly as possible on the surface of the Petri dish with grid on it. We counted the ovules on the dried specimen two or three times each. Mean error of the count was 3.4% (109 ovules per ovary on average). Number of ovules was 1412-4665 (mean±SD: 3210 ±1239) per ovary. We can reveal some dependence of ovules number in ovary even on our modest material. The ovary of small plant with single flower had 1412 ovules. Ovary of the first (lowest) and the second (medium in three-flower inflorescences and upper in two-flower inflorescence) had the similar ovules number (3997±206 and 4016±594 respectively). The upper flowers in three-flower inflorescences had 1719±107 ovules per ovary (fig. 1). We counted ovules from each placenta separately in three ovaries. In two ovaries the differences between placenta did not exceed 10%, but in the third ovary one placenta had two times less ovules then the two others. Thus, one should estimate the potential seed production of Epipogium only on the whole ovaries.
Figure 1. Dependence of ovule number in the ovary on its position in the inflorence
Despite of considerable potential seed production, our data do not demonstrate the significant role of seed reproduction in population maintenance. On the contrary, we have shown that the biggest underground individuals are divided before the formation of generative shoot, and buds are formed on the stolons quite regularly. However, lacking of significant data on the fruitification rate does not let us make any definite conclusions.
This work was made under the treaty between Kandalaksha state nature reserve and Moscow South-West High School.
Kopylov-Gus'kov Yu.O., Volkova P.A., Shipunov A.B., Lyskov D.F., Petrov P.N. Population of Epipogium aphyllum (F.W. Schmidt) Sw. (Orchidaceae Juss.) on the Kem-Ludy archipelago in the White sea // Bulletin MOIP. Dpt. biol. 2007. In press. [in Russian]
Irmish T. Beitrage zur biologie und morphologie der orchideen. Leipzig. 1853. 150 s.
Ziegenspeck H. Orchidaceae. Lebensgeshichte der Blutenpflanzen Mitteleuropas. Bd. 1, Abt. 4. Stuttgart. 1936. 840 s.