30 JOURNAL OF BOTANY VOL. IX, NR. 2 (15), 2017 CZU 581 : 635.92.05 LEAF MORPHOLOGY AND ANATOMY OF SOME SPECIES OF THE GENUS KNIPHOFIA MOENCH Irina Sfeclă Botanical Garden (Institute) of the Academy of Sciences of Moldova Abstract: This article includes several aspects of histo-anatomical characteristics of the leaves of the species: Kniphofia uvaria (L.) Hook., K. ensifolia Bak., K. tukii Bak., K. nelsonii Mast and K. sarmentosa (Andr.) Kunth. Fresh biological material, harvested in 2015, from the specimens found in the collection of non-traditional perennial plants of the Botanical Garden (Institute) of ASM, was used for this study. The morphoanatomical features of the leaves allow determining such characteristics as succulence and water storage capacity, which helps the plants tolerate drought and cope with this stress factor, characteristic of xerophytes. Keywords: Kniphofia, leaf, anatomy, morphology. INTRODUCTION The first studies on the genusKniphofia Moench (red-hot pokers, tritomes) have described the macro- morphological characteristics of the species [5, 7]. Of all the vegetative organs, leaf is the most used in plant taxonomy. Srivastava (1978) described the leaf epidermis as the second most important characteristic, after cytology, in solving taxonomical problems [9]. Leaf anatomy is used by many researchers in the classification of difficult taxonomic groups and, in the case of the genusKniphofia , in solving some uncertainties regarding the specific and generic belonging. A. Berger has done the first descriptions, at anatomical level, of the species of red-hot pokers (tritomes) in his monumental work “Pflanzenreich” vol. IV, which includes descriptions on the genus Kniphofia [5]. In W. Russell’s opinion, this study has many gaps and considers it necessary to carry out a more detailed study on the leaf structure of Kniphofia aloides Moench (syn. Kniphofia uvaria (L.) Hook.) [10]. Baijnath (1980) studied the leaf anatomy of 18 species of red-hot pokers to assess the taxonomic value of the anatomical features of leaves. He discovered that the leaf area and the internal anatomy proved to be useful features, especially for the exclusion of the genus Notosceptrum [1]. MATERIALS AND METHODS The biological material was collected in 2015, from the species: Kniphofia ensifolia Baker, K. uvaria (L.) Hook., K. tukii Baker, K. nelsonii Mast. and K. sarmentosa (Andr.) Kunth. Fresh material was used, from which cross sections were prepared by hand. To detach the epidermis, we used the peeling method. Stomatal density (SD) is the number of stomata per mm2. To determine the SD, we used the micrometric coefficient for each eye piece-objective pair at the microscope Biolam-D-12. Pictures were taken with Kodak AF camera, 8.2 megapixel. The statistical processing of the obtained data was performed by calculating the arithmetic mean and the standard error in the MS Excel program. RESULTS AND DISCUSSIONS The genusKniphofia Moench comprises about 75 species of perennial herbaceous plants, native to southern and eastern Africa, one species is endemic to Madagascar and one – to the southern part of the Arabian Peninsula [6]. For a long time in the post-Linnaean period, the genus Kniphofia was considered part of the Liliaceae Juss. family [2, 5, 6, 12]. At the moment, its taxonomic position is [13]: JOURNAL OF BOTANY VOL. IX, NR. 2 (15), 2017 31 KINGDOM: Plantae PHYLUM: Angiospermae CLASS: Liliopsida (Monocotyledonatae) ORDER: Asparagales Link FAMILY: Asphodelaceae Dumort. SUBFAMILY: Asphodeloideae Burnett. GENUS: Kniphofia Moench The root system of Kniphofias consists of an underground rhizome, which develops numerous fleshy roots [3, 11]. The vast majority of species do not produce an aerial stem [4, 11]. The linear leaves form a dense rosette at the base of the plant [4]. The flowers range in colour from yellow to deep red. They are grouped in compact terminal spikes [4, 11]. The fruits are capsules that produce 8-10 seeds. The seeds are deltoid, 2-3 mm long, green to dark brown. Red-hot pokers are generally cultivated as ornamental plants. Fig. 1. The aspect of the studied species during the abundant flowering stage (1 - Kniphofia uvaria (L.) Hook.; 2 - K. ensifolia Baker; 3 - K. nelsonii Mast.; 4 - K. tukii Baker; 5 - K. sarmentosa (Andr.) Kunth.) Leaf morphology. All the species of Kniphofia have semi-succulent leaves, a character that underlies the delimitation of the genus Kniphofia Moench from the genus Aloe L. [6, 8]. The characteristics of the leaf are often used to distinguish between species. The leaves from the bottom of the rosette die every year. In spring, a new group of 6-20 leaves develops instead (Fig. 2 A, B). The leaves located in the centre of the group are shorter and narrower, more or less filiform. Only the characteristics of the leaves situated outside the annual group were used in the morphological description. 32 JOURNAL OF BOTANY VOL. IX, NR. 2 (15), 2017 Table 1. Morphological characteristics of leaves SPECIES Morphological K. K. characteristics K. uvaria (L.) K. tukii K. nelsonii sarmentosa sarmentosa K. ensifolia Baker Hook. Baker Mast. (Andr.) (Andr.) Kunth. Kunth. 1 8-12 10-20 12-20 12-16 6-8 The number of leaves 2 10.7±1.29 14.3±0.80 16.6±2.31 14.2±1.88 7.4±0.93 in an annual group 3 12.00 20.91 13.97 13.31 12.53 1 56-118 67-81 61-84 65-78 50-65 The length of a leaf 2 88.3±18.8 74.6±1.19 76.2±7.43 71.7±4.56 58.9±4.75 (cm) 3 21.28 5.54 9.74 6.35 8.06 1 1.5-4.5 1.59-1.81 2.6-4.4 2.8-4.6 1.2-3.1 The width at the base 2 3.1±0.89 1.69±0.02 3.6±0.58 3.9±0.60 2.4±0.64 of a leaf (cm) 3 28.89 4.91 16.26 15.33 26.36 1 – maximum and minimum value; 2 – arithmetic mean and standard error; 3 – coefficient of variation Fig 2. Some morphological characteristics of the leaf: A, B – leaf arrangement in the rosette (A – the base of the rosette of K. uvaria (L.) Hook. in cross section, B – K. nelsonii Mast.); C – the toothed margin of the leaf of K. nelsonii Mast.; D – the entire margin of the leaf of K. tukii Baker JOURNAL OF BOTANY VOL. IX, NR. 2 (15), 2017 33 The studied species have linear, long acuminate, opposite leaves (Fig. 2 A, B). The leaves of some species can be arched or recurved (Kniphofia ensifolia, K. uvaria), but most of them are at first erect and later geniculate from the middle (K. nelsonii, K. sarmentosa and K. tukii). A more rigid and fibrous texture is characteristic of K. uvaria. The midrib, on the upper side of the leaf, is canalicular and, on the lower side, is smooth or toothed and hull-like. The margin of the leaf blade is entire (K. ensifolia, K. tukii) or toothed (K. nelsonii, K. sarmentosa, K. uvaria) (Fig. 2 C, D). The teeth are 1-2 mm long. The leaf surface is glabrous in all the studied species. The thickness of the leaf is about 2 mm and is determined by the colourless palisade parenchyma. The large thickness of the leaf blade demonstrates the xeromorphism of the studied taxa. In cross section, the leaf blade is V-shaped at the base and Y-shaped at its tip (Fig. 2 A, B). The biometric analysis of the leaves of the studied species is presented in Table 1. The rosettes with a larger number of leaves are characteristic ofK. uvaria and K. tukii, but the coefficient of variation of this feature is also higher inK. uvaria. Longer leaves are characteristic of K. ensifolia. With regard to the width of the leaf at the base, we can also highlight K. uvaria, which has the lowest index, of 1.69 ± 0.02 cm. Leaf anatomy. In terms of structure of the cross section, the leaf of Kniphofia consists of epidermis, mesophyll and vascular tissue (Fig. 3). Both epidermises are similar, consisting of a cell layer, with well-defined cuticle, made of prosenchymal cells (Fig. 3 A). The studied species have amphistomatic leaves, diacytic stomata with two accessory cells, characteristic of xeromorphs (Fig. 3 E). Their density on the upper epidermis, as well as on the lower one is on average 20-30 per mm2 (Fig. 3 C, D). In comparison with the mesophytes (SD 1200/mm2 – Filipendula ulmaria (L.) Maxim.; millions/mm2 – Helianthus annuus L.), the stomatal density in xerophytes is lower (SD 10/mm2 – Sedum acre L.) [14]. The mesophyll is isolateral. Under each epidermis, there are 1-2 layers of palisade cells, followed by lacunar tissue, rich in chlorophyll. The central part of the mesophyll consists of a colourless parenchyma composed of cells that are much larger than the cells of the palisade and lacunar tissue, of a rounded shape, which has storage function. The vascular bundles are quite numerous and located in lacunar tissue. They are arranged in two parallel rows, delimited by the colourless parenchyma. The midrib is more prominent on the underside and constitutes a vascular bundle (Fig. 3 A, B). 34 JOURNAL OF BOTANY VOL. IX, NR. 2 (15), 2017 Fig. 3. Leaf anatomy (Kniphofia ensifolia Baker): A – cross section of the leaf blade; B – cross section of the midrib; C – upper epidermis; D – lower epidermis; E – the shape of a stoma. 1 – upper epidermis; 2 – lower epidermis; 3, 4, 5 – mesophyll (3 – palisade cells, 4 – lacunar tissue, 5 – colourless parenchyma); 6 – vascular bundle; 7 – midrib CONCLUSIONS The morphoanatomical features of the leaf of the studied species ofKniphofia allow determining such characteristics as succulence and water storage capacity, which helps the plant tolerate drought and cope with this stress factor, characteristic of xerophytes.