VARIABILITY OF MORPHOLOGICAL FEATURES OF NEEDLES, SHOOTS AND SEEDS OF TAXUS BACCATA L. IN NATURE RESERVATIONS OF SOUTHERN POLAND

Marcin Zarek
Department of Forest Pathology, Agricultural University, Cracow, Poland

ABSTRACT

The aim of this research was to enlarge knowledge about variation between populations of the English yew from southern Poland. This aim was realized by investigating morphological features of needles, shoots and seeds of yews from southern Poland. Researches show that there are significant differences in morphological features between populations from southern Poland. The lowest diversity between individuals was found in the nature reserve “Liswarta”, while the highest one was found in “Mogilno” and “Cisowa Góra” for the features of needles and seeds respectively. Average length of needles of Taxus baccata individuals growing in southern Poland is 23.5 mm (range from 15.4 to 36.6 mm), width – 2.4 mm (range from 1.8 to 3.1 mm), area – 57 mm² (range from 32.4 to 94.5 mm²), relation between needle length and width (slim coefficient) – 9.8 (range from 6.8 to 14.3), dry matter of 1000 needles – 5.11 g (range from 1.7 to 17.5 g). Needles dimensions depend on individual genotype and grow simultaneously with age. The results obtained for needles age groups are highly correlated. Needles dry matter is high correlated with precipitation on corresponding nature reserve area and show the highest variability. Average yearly increment of shoots is 5 cm (range from 1 to 16 cm) and depends on genetic and environmental factors together. Average length of seeds is 5.6 mm, width – 4.4 mm and thickness – 4.0 mm. Average wet and dry matter of 1000 seeds is 54 and 47 g respectively and is high correlated with seeds dimensions.

Key words: morphological features, needles, seeds, shoots, Taxus baccata L., variability, yew.

INTRODUCTION

There is a little problem with Taxaceae Lindl. family from botanical point of view. Sometimes it is located in a separate order Taxales and another time it is connected together with Podocarpaceae and Cephalotaxaceae [16]. Division inside the family also isn’t unequivocal. In Taxaceae family from three [3] to five genus [22] can be distinguished: Amentotaxus, Torreya, Austrotaxus, Pseudotaxus and Taxus but only the last one is present in Europe and Poland. Nowadays opinions predominate that there are 8 Taxus species [3]:

• Taxus baccata L. (Europe & Asia),

• Taxus cuspidata SIEB. et ZUCC (Asia – Japan),

• Taxus celebica SIEB. et ZUCC (Asia),

• Taxus wallichiana ZUCC (Asia – Himalayas),

• Taxus brevifolia NUTT (North America – Pacific northwest coast),

• Taxus canadensis MARSH (North America – Canada),

• Taxus floridana NUTT (North America – Florida),

• Taxus globosa SCHLECHDT (North America – Mexico).

Other authors [6, 15] reported that there was only one species Taxus baccata which had local subspecies distinguished on the basis of origin and morphological features. Krussmann [11] tried to characterize all 8 species on the basis of morphological features and their origin but his results are controversial because they depend on age and development stage of trees. Most of species are characterized by high morphological variation what makes that individuals with similar phenotype can be found in different species. That makes the origin be the only one distinguishing factor. Different authors try to use other features such as specific chemical compounds concentration [5, 16] or genome DNA analysis [4]. There are also two hybrids: Taxus x media Rehder., which is a hybrid of Taxus baccata and Taxus cuspidata, and Taxus x hunnawelliana Rehder. (hybrid of Taxus cuspidata and Taxus canadensis).

The high variation inside species makes possible to distinguish varieties. In Poland Stecki and Bella [19] distinguish four natural varieties depending on morphological features of needles: Taxus baccata var. cuspidata, Taxus baccata var. polonica, Taxus baccata var. typica and Taxus baccata var. linearis.

There are also many varieties of Taxus sp. in floriculture what considerably makes difficult botanical classification. Variation of Taxus baccata is high, so in horticulture forms and varieties are often used instead of species. Only for Taxus baccata over 100 varieties was described [1].

There are two contradictory theses about variability of yew in the world literature. According to Stebbins [18] yew is an old phylogenetic species, so it is little variable. Another thesis is presented by Stecki and Bella [19] and Bugała [3] who maintain that in spite of yew which is an old phylogenetic species it evolves creating new forms and varieties.

The main aim of our research was to verify so far found data and explain doubts. Many biometrical studies were performed to determine morphological variability of Taxus baccata individuals from southern Poland.

MATERIALS AND METHODS

Plant material
Plant material was represented by needles, shoots and seeds of Taxus baccata and was collected in nine nature reservations:

• “Cisy koło Sierakowa”,

• “Cisy na Górze Jawor”,

• “Cisy w Nowej Wsi”,

• “Cisy w Hucie Starej”,

• “Malinówka”,

• “Cisowa Góra”,

• “Zadni Gaj”,

• “Cisy w Mogilnie”,

• “Cisy nad Liswarta”.

Plant material was collected in late October. Shoots (4 samples from each tree) were collected from 20–30 trees in every reservation. Shoots were sprinkled and placed separately in polyethylene bags for a transport time. In the laboratory measurement of shoots annual growth and parameters of three age groups of needles was performed (for every age group separately). Every age group of needles from every tree was represented by 80–120 needles. Besides, in each reservation, seeds from 20 female individuals were colleted. It was measured one hundred seeds from each reservation.

Measurements
Length (L) width (W), area and dry matter were measured for needles and “slim coefficient” (relation between needle length and width) was calculated. Length (L), width (W), thickness (T), wet and dry matter were measured for seeds and shape coefficients were determinated: L/W (length to width ratio), L/T (length to thickness ratio) and W/T (width to thickness ratio). Measurements of shoots annual growth and seeds dimensions were performed directly. Needles were scanned and the program for image analysis was used (Image Analysis System LUCIA^®). To determinate dry matter all needles and seeds were dried for 24 hours in 105°C and were weighed on the analytical balance. Hydration level was computed as a difference between wet and dry matter.

Statistical analysis
For every obtained data average value, range, standard deviation and coefficient of variation were calculated. To determinate if average values differ significantly from each other analysis of variance and post hoc analysis were performed by Duncan test at significance level α=0.05. Statistical analysis of obtained results was performed by using computer program (Statistica 5.1 Pl.)

RESULTS AND DISCUSSION

By different authors length of Taxus baccata needles ranges from 10 to 44 mm [3, 7, 8, 9, 12, 17, 19, 21, 22]. Horticultural varieties have usually needles shorter than nominative species [5]. In our research individuals had average length 23.5 mm and range from 15.4 to 36.6 mm (Table 1) what confirms prior studies. Also the average width of measured needles (average 2.4 mm and range from 1.85 to 3.1 mm – Table 2) is according to literature data [3, 5, 7, 8, 9, 12, 17, 19, 21].

The area of needles is strongly correlated with their length (correlation coefficient 0.91 – Table 12) and less with width (correlation coefficient 0.86 – Table 12). Unfortunately so far this feature hasn’t been investigated by most authors, what makes comparison very difficult. The obtained results (Table 3) shows average needles area of about 57 mm² and this value is higher than observed by Dempsey and Hook [5] on individuals growing in Great Britain (26.5 – 42.2 mm²). In our research this value ranges from 32.4 to 94.5 mm². That difference is mainly caused by larger width of measured needles but also by their length. It was observed very interesting effect of declined needles area and width together with elongation of vegetation period. The correlation coefficient computed for these features was -0.71 and -0.82 (Table 12) respectively and was statistically significant. That tendency is also confirmed by results obtained in England [5] where vegetation period is longer than in Poland and both needles width and area are smaller than for individuals growing in Poland.

In Poland Stecki and Bella [19] distinguished four botanical varieties depending on slim coefficient (S – length to width ratio): var. cuspidata (S=7–8), var. typica (S=9.7–11.5), var. polonica (S=13.4–13.6) and var. linearis (S=14.3–16.7). But researches made by Kuswik [12] show that in populations growing in Poland average slim coefficient ranges from 6.56 to 11.83 and most often between 9 and 10 what makes possible to classify them as Taxus baccata var. typica. He observed also high individuals variation inside population ranged from 3.86 to 20.0 with average value 9.91. In case of yews from southern Poland (Table 4) where we investigated needles slim coefficient changes in lower range (from 6.8 to 14.3), and average value (9.8) is in accordance with Kuswik’s [12] results. There are individuals from all varieties distinguished by Stecki and Bella [19] in every reservation investigated by us (Table 5). Varieties linearis which is observed only in 1.1% of individuals growing in reservation “Cisowa Góra” is the one exception. Data indicates that slim coefficient is an individual feature not connected with concrete population and can’t be acknowledged as a real varieties indicator.

Together with the age of needles all of their features (length, width, area, and dry matter) grow (Table 1, 2, 3 and 6). That shows that the needles grow not only in first but also in second and third year.

Dry matter of needles isn’t correlated with other features (area, length, width) what can indicate that the needle thickness has the main influence on this feature. There is a high correlation (r=0.76 – Table 12) between needle dry matter and precipitation what confirms a positive effect of moisture on yew growing [10].

Annual growth of shoots depends on many genetic and environmental factors. Bugała [3] reports that yew is a slow growing tree, especially older individuals, but young trees can attain high annual growth (30 – 40cm for leader shoot). Our researches (Table 7) show high variation of this feature but on a low level (from 1 to 16 cm for a year). An average value of 5 cm what we obtained confirms thesis [3] about slow growing of a yew.

Length of yew seeds ranges from 4 to 8 mm [3, 7, 12, 17, 20], width from 2 to 5 mm [3, 7, 12] and their thickness ranges from 4.0 to 4.5 mm [12]. That is confirmed by our researches. We obtained average seeds length 5.6 mm, width – 4.4 mm and thickness about 4.0 mm (Table 8).

Also seeds shape coefficients computed by us correspond to those presented by Kuswik [12].

An average wet matter of 1000 seeds (54 g – Table 10) and dry matter (47 g – Table 10) correspond to data for Poland region [13, 20] and are strongly correlated with seeds dimensions (Table 12). But they are smaller than seeds from individuals growing in Holland (wet matter of 1000 seeds about 77g) [20].

There are two contradictory theses about variability of yew in the world literature. According to Stebbins [18] yew is an old phylogenetic species, so it is little variable. Another thesis is presented by Stecki and Bella [19] and Bugała [3] who maintain that in spite of yew that is an old phylogenetic species, it evolves creating new forms and varieties. By Kuswik [12] a range of extreme values of seeds and needles features is very big, but average values are little diversified. Standard deviation doesn’t exceed 23% for needles features and 15% for seeds. In our research (Table 1, 2, 3, 4 and 6) the highest diversification characterizes dry matter of 1000 needles for which average standard deviation is about 36% and for special cases (“Cisy na Górze Jawor”) achieves 47%. According to Kuswik [12] and also our research (Table 8, 9 and 10) seeds are less variable than needles. As well in this case the highest standard deviation was for matter of 1000 seeds. Different authors [2, 14, 18] pay attention to less variation of generative than vegetative organs what is caused by lesser environmental effect.

As distinct from Kuswik’s [12] results, who pay attention to higher intrapopulation variability, our statistical analysis shows significant differences between populations (Table 11). The highest differences are observed by needles features. All populations differ significantly from each other in respect of needles length and width. In respect of needles area only two reservations: “Sieraków” and “Góra Jawor” do not differ significantly. Lesser diversification between populations in respect of shoots and seeds features were observed.

CONCLUSIONS

There is together diversification between populations and individuals variability what confirms thesis that though yew is an old phylogenetic species it is characterized by high variation.

ACKNOWLEDGMENTS

This research has been supported by the Polish Committee for Scientific Research (KBN) under Contract No. 0442/P06/2002/23. The author acknowledges for the financial support for this study.

REFERENCES

1. Appendino G. 1993. Taxol (paclitaxel): historical and ecological aspects. Fitoterapia 64, 5-25.

2. Bałut S. 1969. Zmiennosc szyszek modrzewia jako podstawa wyróżniania pochodzeń. [Variability of a larch cones as a base to distinguish provenances]. Act. Agr. Silv. Ser. Silv. 9, 3-109 [in Polish].

3. Bugała W. 1975. Systematyka i zmiennosc. [Systematics and variability]. (In:) Cis pospolity (Taxus baccata L.). [Common yew]. Białobok S. (ed.). PWN, Warszawa-Poznań, 18-38 [in Polish].

4. Corradini P., Edelin C., Bruneau A., Bouchard A. 2002. Architectural and genotypic variation in the clonal shrub Taxus canadensis as determined from Random Amplified Polymorphic DNA and Amplified Fragment Length Polymorphism. Can. J. Bot. 80, 205-219.

5. Dempsey D., Hook I. 2000. Yew (Taxus) species – chemical and morphological variations. Pharmaceutical Biology 38, 274-280.

6. Elwes H. J., Henry A. H. 1906. The trees of Great Britain and Ireland. Sr Publishers ltd., 1, 98-126.

7. Henneberg M., Skrzydlewska E. 1984. Zatrucia roslinami wyższymi i grzybami. [Poisoning by higher plants and mushrooms]. Państwowy Zakład Wydawnictw Lekarskich, Warszawa. [in Polish].

8. Kapusciński S. 1947. Cis jako roslina żywicielska. [Yew as a host plant]. Wszechswiat 8, 267-272 [in Polish].

9. Król S. 1972. Siewki drzew i krzewów. [Seedlings of trees and shrubs] PWRiL, Warszawa. [in Polish].

10. Król S. 1975. Zarys ekologii. [An ecological outline]. (In:) Cis pospolity (Taxus baccata L.). [Common yew]. Białobok S. (ed.). PWN, Warszawa-Poznań, 78-103 [in Polish].

11. Krussmann G. 1972. Handbuch der nadelgeholze. [Handbook of conifers]. Verlag Paul Parey, Berlin-Hamburg [in German].

12. Kuswik H. 1987. Zmiennosc morfologiczna cisa pospolitego (Taxus baccata L.) w Polsce. [Morphological variability of Taxus baccata in Poland]. Roczn. Dendr. 37, 25-60 [in Polish].

13. Lewandowski A. 1999. Significant differences in seed germination among seed lots from individual of Taxus baccata L. after ten months of stratification. Arboretum Kórnickie 44, 130-136.

14. Mejnartowicz L. 1972. Badania zmiennosci populacji Alnus glutinosa (L.) Gaertn. w Polsce. [Variability of Alnus glutinosa (L.) Gaertn populations in Poland]. Arboretum Kórnickie 17, 43-120 [in Polish].

15. Pilger R. 1916. Die Taxales. [The Taxales]. Mitt. D. D. Dendr. Ges. 25, 1-30 [in German]

16. Rozendaal E. L. M., Kurstjens S. J. L., Beek T. A., Berg R. G. 1999. Chemotaxonomy of Taxus. Phytochemistry 52, 427-433.

17. Seneta W. 1981. Drzewa i krzewy iglaste. [The coniferous trees and shrubs] PWN, Warszawa. [in Polish].

18. Stebbins G. L. 1958. Zmiennosc i ewolucja roslin. [Variability and evolution of plants]. PWN, Warszawa. [in Polish].

19. Stecki K., Bella E. 1931. Studia biometryczne nad cisem (Taxus baccata L.) w Polsce. [Biometric studies of Taxus baccata in Poland]. Roczn. Dendr. 4, 1-14 [in Polish].

20. Suszka B. 1975. Generatywne i wegetatywne rozmnażanie cisa. [Generative and vegetative reproduction]. (In:) Cis pospolity (Taxus baccata L.). [Common yew]. Białobok S. (ed.). PWN, Warszawa-Poznań, 104-124 [in Polish].

21. Szaniawski R. 1975. Zarys fizjologii cisa. [Outline of physiology]. (In:) Cis pospolity (Taxus baccata L.). [Common yew]. Białobok S. (ed.). PWN, Warszawa-Poznań, 66-77 [in Polish].

22. Tomanek J. 1997. Botanika lesna. [Forest botany]. PWRiL, Warszawa. [in Polish].

Accepted for print: 3.07.2007

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