ABSTRACT

The genus Vicia L. includes about 190 species around the world and approximately 40 species in China. The genus includes minor food crops and forage plants. This study gives a detailed description of foliar structure of some Vicia species from China. Leaf characters showed considerable variation among studied taxa including petiole and tendril length; leaflets number, length, width, shape, apex, base; blade surface, trichome shape, type, base and length; stipules shape, base, length, width and surface. Numerical analysis of these characters was used to construct a phenogram illustrating the relationship between the studied taxa and to build an artificial key to identify Vicia species. Moreover, variation in leaf characters helped in overcoming the overlapping among harmful taxa.

Keywords:

Vicia, Fabaceae, Stipules, Trichomes, Numerical Taxonomy, Micro-Morphology

1. Introduction

Taxonomic significance of the foliar structure has been well documented [1] [2] [3]. Leaf micro-morphological characters show systematic significance in different levels in family Fabaceae [4] [5] [6]. Trichomes micro-morphology is one of the most significant leaf micro-morphological characters studied in species of different genera [7] [8].

The genus Vicia L. of the Fabaceae family includes about 190 species [9]. About 40 species have economic importance. The genus includes some minor food crops and more than a dozen forage plants; the most important is common vetch, V. sativa, cultivated in many countries [10].

Taxonomic delimitation is necessary to solve the overlapping between economic crops and harmful species. Morphological characters of leaf feature which may provides information for understanding species relationship in the genus Vicia, have not been studied. This work was initiated with the objectives of using leaf features to identify taxa.

2. Material and Methods

2.1. Seed Source and Morphological Examination

Vicia species seeds in this study were obtained from Desert Legume Program (DELEP) and The Germplasm Bank of Wild Species, Southwest China.

Seeds of each taxon were germinated in perlite sand; Ten days after germination (Seed were treated as germinated when the radical protruded from the envelopes), the young seedlings were transferred to pots containing peat moss soil. 60 days later, complete leaves were collected from each taxon, all the leaves were collected from the fifth nodes.

Stereo-microscope and light microscope were used for morphological measurement of the leaves.

2.2. Statistical Analysis

The extracted leaf characters were coded as 1 to 0 codes and used for numerical analysis; forty eight characters were recorded for each taxon. Phenogram illustrating the relationship between the studied taxa were constructed using the NTsys2.1 [11].

3. Results and Discussion

Considerable variation of leaf characters were observed among studied taxa as shown in Figures 1-3; for example, leaf consisted of 2 leaflets or 4 - 8 leaflets with their shape varying from elliptic, lanceolate, oblong, obovate to ovate. Leaflet apex was acute, acuminate, obtuse or truncate and the base was cuneate or obtuse. Leaf surface was hairy to glabrous. Stipules shape varied from sagittate to hastate with acute to forked base. Observed variations summarized in Table 1 and Table 2 enabled us to identify species.

Several natural systems had been constructed to divide the genus Vicia based on morphological characters such as stems, flowers, and fruits [12]-[17]. In addition to species identification, this work leaf characters were used to help in overcoming the overlapping among these systems.

In the natural system of [18], V. sativa subsp. nigra was treated as V. angustifolia subsp. pusilla; on the other side, [12] treated it as a subspecies of V. sativa; this suspicion may be dangerous as V. angustifolia is an important forage plant, belonging to the first group of fodder vetches [13], while V. sativa ssp. nigra is possibly contains gluco-alkaloids and neurotoxic cyanoamino acids which have toxic effect [19]. The phenogram in Figure 4 show that V. sativa subsp. nigra is more closely related to V. sativa (0.2 - 0.5 mm, acute, multicellular trichomes

with glandular base) and not to V. angustifolia (1 - 2 mm, linear, unicellular trichomes with non-glandular base) supporting the classification of [12].

An artificial key to Vicia species was constructed as follow:

1a. Leaflets obovate, V. bungei

1b. Leaflets elliptic (2)

2a. Blade with multicellular trichomes (3)

2b. Blade smooth or with unicellular trichomes (4)

3a. Leaflets ovate. Stipules base forked V. sativa subsp. sativa

3b. Leaflets lanceolate. Stipules base acute V. sativa subsp. nigra

4a. Leaflets blade hairy (5)

4b. Leaflets blade smooth (8)

5a. Leaflets oblong. Blade surface with linear trichomes (6)

5b. Leaflets lanceolate or ovate. Blade surface with acute trichomes (7)

6a. Blade with 0.1 to 0.5 mm distances between trichomes. Stipules with hairy surface V. angustifolia

6b. Blade with more than 2 mm distances between trichomes. Stipules with smooth surface V. villosa subsp. dasycarpa

7a. Leaf with 2 leaflets V. tenuifolia

7b. Leaf with 4-8 leaflets V. villosa subsp. varia

8a. Stipules with forked base V. hirsuta

8b. Stipules with acute base (9)

9a. Leaflets elliptic. Stipules hastate V. tetrasperma

9b. Leaflets lanceolate or oblong. Stipules sagittate (10)

10a. Leaflets with obtuse apex and cuneate base V. japonica

10b. Leaflets with acute or acuminate apex and obtuse base (11)

11a. Leaflets oblong V. costata

11b. Leaflets lanceolate V. amoena

In conclusion, our results show that leaf morphological characters are variable and helpful in distinguishing various species and could be used to construct an artificial key to identify Vicia species.

Acknowledgements

This study was supported by the National Natural Science foundation of China (Grant No. 31370007).

Cite this paper

Abozeid, A., Liu, Y., Liu, J. and Tang, Z.H. (2017) Comparative Foliar Structure of Vicia L. Species from China. Journal of Biosciences and Medicines, 5, 170-175. https://doi.org/10.4236/jbm.2017.53018

References