Philippine Journal of Science 145 (3): 259-269, September 2016 ISSN 0031 - 7683 Date Received: ?? Feb 20??

Xerophytic Characteristics of philippinensis Benth. & Hook. f.

Jonathan O. Hernandez1, Pastor L. Malabrigo Jr.1, Marilyn O. Quimado1*, Lerma SJ. Maldia1, and Edwino S. Fernando1

1Department of Forest Biological Sciences, College of Forestry and Natural Resources, University of the Philippines Los Baños, College, Laguna

Tectona philippinensis Benth. & Hook.f. is one of only three species in the genus Tectona () restricted to the Asian tropics. It is endemic to Ilin Island and Batangas Province on Luzon Island, Philippines and is regarded as a critically endangered species. While role of xerophytic characteristics of are very important for their survival and growth under various environmental pressures, such characteristics in native tree species remain unclear. In this study, the anatomy of the species was analyzed to determine the xerophytic characteristics of T. philippinensis. Histological paraffin technique was used to examine the anatomical structures of leaf and young stem of the species. The anatomical structures of T. philippinensis have the characteristics typical of xerophytic plants. This includes the presence of four types of trichomes, extended and well-developed vascular system, and multiple layers of palisade and sclerenchyma cells. Extension of extended vascular bundles to both non-glandular hairs on the adaxial surface and glandular hairs on the abaxial surface of leaf is reported for the first time in this study. Therefore, anatomical structures of this species suggest its ability to survive under marginal conditions. However, studies on ecophysiology, pot experiments/field trials, phenology, and associated vegetation of the species are suggested to further understand its habitat preference and adaptation mechanisms.

Key words: anatomy, arid or semi-arid, endemic, Lamiaceae, restoration, xerophytes.

INTRODUCTION T. philippinensis is known only from Ilin Island and Batangas Province on Luzon Island, usually along dry The genus Tectona L.f. (Lamiaceae) includes only three hills and exposed limestone ridges along the coasts and species of trees restricted to the Asian tropics, viz., is also deciduous (Caringal et al. 2015). It is commonly Tectona grandis L.f. occurring in India, Laos, Mynamar, called Philippine , but is also known locally by the and Thailand; Tectona hamiltoniana Wall., endemic to vernacular names malabayabas and bunglas. The species Myanmar; and Tectona philippinensis Benth. & Hook.f., is regarded as critically endangered (Fernando et al. 2008, endemic to the Philippines. T. hamiltoniana occurs in the Madulid et al. 2008). The few remaining populations central dry zone of Myanmar (Kiyono et al. 2007; Aye et have been reported to be threatened by habitat destruction al. 2014), while T. grandis is known from a wider range through land conversion and development. Significant of climatic conditions, including dry areas, throughout its conservation efforts of the species include the Biodiversity natural range (Kaosa-ard 1981; Gyi & Tint 1998). Both Management Bureau (BMB) initiated project on ex-situ these species are known to be deciduous trees. conservation areas for the Philippine teak (PAWB-DENR *Corresponding author: [email protected]

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1998) and non-government organizations and academe apical portion of an orthotropic branch. For leaf sample, initiated certain in-situ conservation strategies (Agoo & a small piece measuring 1mm2 was transversely cut in Oyong 2008). the median to include the midrib. For stem sample, on the other hand, approximately 1-2 mm long was also Many anatomical characteristics have been recognized transversely cut along the main axis of the stem using as protective mechanisms that allow the plants to survive a sharp Gillete razor blade. The illustrations of these against various levels of environmental pressure. For procedures are presented in Figure 1. example, the seven types of trichomes and their density through in vivo leaves of T. grandis were linked to extreme Histological paraffin technique was used (Johansen 1940) dependence of the species, especially those young ones, (Figure 2). Samples were fixed in 1:1 mixture of FAA-A for storing water during the developmental stage. In (12ml 37% Formaldehyde, 88ml 95% Ethanol) and vitro leaves, on the other hand, due to poor development FAA-B (10ml Glacial Acetic Acid, 88ml, and 90ml water) of epidermal structures (e.g. trichomes) were reported for three weeks. They were dehydrated following series of to have higher water loss than those of in in vivo leaves solutions of water, ethyl, and tertiary butyl alcohols from (Bandyopadhyay et al. 2004). Stephanou & Manetas 50% to 100% for four days. Gradual infiltration followed (1997) reported the features of leaves enable plants to using a 1:1 mixture of paraffin oil and tertiary butyl tolerate adverse conditions in the site such as drought, high alcohol for three days in the oven at 650C. Embedding the air temperature, UV-B radiation, among others. Plants that samples in the melted condition of paraffin wax followed. are well-adapted to such conditions commonly referred The samples were then mounted into 1.5cm x 1.5cm x 2cm to as xerophytes exhibit certain adaptive mechanisms to wooden blocks. Mounted samples were sectioned using a complete their life cycle in dry environments (Atia et al. rotary microtome (American Optical 820) at a thickness of 2014). They have special modifications such as leaves 10µm. Cross sections were mounted on microscope slides that are trichomous, with thick cuticle (Richardson & coated with Haupt’s solution, air-dried for three days, and Berlyn 2002), high palisade tissue/spongy tissue ratio, stained with 1% Safranin and were counter stained with and well developed water-storing and water-transporting 0. 5% Fast green. tissues to minimize the rate of transpiration. Many of the species in the family Lamiaceae have long been reported Microscopic examination and analysis to have xerophytic characteristics such as in the case of The typologies of anatomical structures were identified Salvia sclarea L. (Ozdemir & Senel 1999), Teucrium following the manual on anatomy of dicot plants. The montanum L. and Teucrium polium L. (Dinç et al. 2011). thicknesses of all visible dermal, ground, and vascular There is no report yet on xerophytic characteristics of tissues were measured. Characteristics of other structures T. philippinensis. This study analysed the anatomical such as stomata and trichomes were also examined. structures (leaf and young stem) of T. philippinensis to determine the species’ xerophytic characteristics. All the cross sections obtained were observed under a compound microscope (Euromex 0112987, manufacturer: BlueLine Holland) equipped with a camera which was connected to a desktop computer. The scale of all the MATERIALS AND METHODS measurements was calibrated at 40x magnifications. The mean thicknesses of the observed anatomical Place and duration of the study structures for both species were calculated using some The anatomical examination of leaf and stem was functions in MS Excel. Comparison of anatomical conducted at the Microtechnique Laboratory of the structures between T. philippinensis and C. ramiflora Department of Forest Biological Sciences (DFBS), was made. College of Forestry and Natural Resources (CFNR), University of the Philippines Los Baños (UPLB) from August to October 2015. RESULTS Preparation of specimens Three sample replicates for each leaf and stem of T. Stem philippinensis were collected from Lobo, Batangas, The stem of T. philippinensis is six-angled (Figure 3) and located at 400 masl. Samples of a non-xerophytic , its surface is occupied with glandular trichomes – capitate, Cynometra ramiflora L. were collected from Arbor peltate, and branched (Figure 5). The hypodermis is four Square, CFNR - UPLB. The leaf and/or stem sample for to six-layered of collenchyma cells. The rest of the cortex both species was obtained from c.a. 6-8 cm long from the is composed of 591.2µm thick, oval to round parenchyma

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Figure 1. Young leaf and stem of an orthotropic branch as the plant material of the study showing (a) length of sample used (b) part of leaf where the samples were obtained (c) size of cross section samples put inside the microcentrifuge tubes and (d) size of stem samples put inside the microcentrifuge tubes.

Figure 2. Procedures of paraffin technique used in this study showing (a) fixation (b) dehydration (c) infiltration (d) embedding (e) microtoming (f) mounting on slide (g) staining (h) microscopic examination which were conducted at Microtechnique Laboratory of CFNR-UPLB. cells with intercellular spaces. The vascular tissue is of The pith enclosed by the vascular cylinder is built up collateral bundle type, measuring 1504.2µm thick, where of round and polygonal parenchymatous cells and 4-5 the xylem is of endarch configuration (Figure 3). Xylem clumps of compactly arranged thick walled sclerenchyma measures 383.0µm. Xylem fibres and xylem parenchyma cells (Figure 3). were also present. The phloem cells are small, polygonal, measuring 323.6µm in thickness. There are 2-3 layers The mean thickness of each of the observed anatomical of phloem sclerenchyma- fibres (294.9µm thick) that structures of C. ramiflora is presented in Table 1. Stem cap the phloem cells. Phloem parenchyma and xylem is irregular in shape without trichomes in its surface parenchyma were also observed in the vascular bundles. (Figure 4). Epidermis is single-layered of round to

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Figure 3. Stem cross section of T. philippinensis showing (a) overview of stem (b) simple and complex tissues, and (c) sclerenchyma cells in pith. Abbr.: ep – epidermis, p – parenchyma, sc – sclerenchyma, co – collenchyma, ph – phloem, xy – xylem, and vb –vascular bundle. The bar represents 100µm. oval-shaped epidermal cells. The hypodermis is one and glandular branched on the abaxial surface (Figure 5). to two-layered of collenchyma cells, which measure Stomata are of hypostomatic type. The palisade mesophyll 238.0µm in thickness. Next to it is the cortical layer (336.5µm thick) is one to two-layered of elongated which is built up of two to three layers of parenchyma parenchymatic cells. The spongy mesophyll (444.4 µm) cells. This layer measures 329.2µm in thickness. is multi-layered. The vascular bundles in the secondary There are four to five vascular bundles. Each measures veins are transcurrent. (Figure 6b). The xylem (49.5µm 702.8µm in thickness. These vascular bundles are of thick) faces toward the upper epidermis while the phloem collateral type. Xylem and phloem measure 386.4µm (13.8µm thick) faces toward the lower epidermis (Figure. and 316.4µm thick, respectively. There are one to two 6a). In the midrib, the phloem is found in both sides of the layers of sclerenchyma cells (158.0µm thick) which form xylem (Figure 6a). Three to six layers of sclerenchyma the phloem cap. Pith is parenchymatic. cells that cap the phloem toward the periphery. Thick layer of parenchyma cells (1390.4 µm thick) in either side of main strand of vascular bundles was observed. Thick Leaf sclerenchyma cells that cap the phloem cells were present. The average thickness of each observed anatomical structure in leaf of T. philippinensis is presented in Table 1. The freehand cross section of leaf of C. ramiflora and Both epidermises are uniserriate. Lower epidermis is wavy the average measurement of each observed anatomical in appearance (Figure 6b). Using the works of Serrato- structures are presented in Figure 7 and Table 1, Valenti et al. (1997), Ascensa~o et al. (1999), Zheng respectively. Upper and lower epidermises are uniserriate. (2001), Gersbach (2002), Huangz et al. (2008), four types The former measures 70.7µm while the latter measures of trichomes were identified, namely: non-glandular on 93.4µm in thickness. The palisade mesophyll is single- the adaxial surface, glandular capitate, glandular peltate, layered of oblong to columnar parenchymatic cells. This

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Table 1. Average thickness in micrometers of anatomical parts of stem and leaf of Tectona philippinensis and Cynometra ramiflora. n=3 leaf/stem samples. LEAF T. philippinensis C. ramiflora Upper epidermis 99.1 70.7 Lower epidermis 95.6 93.4 Palisade mesophyll 336.5 220.9 Spongy mesophyll 444.4 329.2 Midrib 4932.6 1644.2 Parenchyma (midrib) 1390.4 327.6 Sclerenchyma (midrib) 488.5 244.2 Collenchyma (midrib) 839.6 279.5 Vascular bundles (midrib) 2603.9 1252.0 Vascular bundles (blade) 952.0 452.2 Xylem 358.0 279.7 Phloem 194.8 182.5 STEM T. philippinensis C. ramiflora Epidermis 27.0 26.0 Parenchyma 591.2 329.2 Sclerenchyma 294.9 158.0 Collenchyma 389.7 238.0 Vascular bundles 1504.2 702.8 Xylem 383.0 386.4 Phloem 323.6 316.4

Figure 4. Freehand stem cross section of T. philippinensis showing (a) overview of stem (b) simple and complex tissues, and sclerenchyma cells in pith. Abbr.: ep – epidermis, p – parenchyma, sc – sclerenchyma, co – collenchyma, ph – phloem, xy – xylem, and vb – vascular bundle. The bar represents 50µm. layer measures 220.9µm thick. The spongy mesophyll 1644.2µm in thickness. In the midrib, one to two layers is multi-layered which measures 329.2µm thick. The of collenchyma cells (279.5µm) next to epidermis are vascular bundles in the secondary veins are of embedded observed. This is followed by only two to three layers of type of pattern. The xylem (279.7µm thick) faces toward parenchymatous cells (327.6µm thick) towards the main the upper epidermis while the phloem (182.5µm thick) strand of vascular bundles (1252.0µm thick). One to two faces toward the lower epidermis (Figure 7a). The midrib layers of sclerenchyma cells in the form of phloem cap is adaxially convex and abaxially concave. This measures cells (244.2 µm thick) surround the vascular bundles.

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Figure 5. Trichomes observed in stem and leaf of T. philippinensis showing (a) non-glandular type in adaxial surface of leaf, (b) capitate glandular type in leaf and stem (c) peltate glandular type in leaf and stem, and (d) branched glandular type in leaf and stem. The bar represents 100µm.

Figure 6. Leaf cross section of T. philippinensis showing (a) midrib and (b) leaf blade. Abbr.: p – parenchyma, sc – sclerenchyma, co – collenchyma, nt – nonglandular trichome, pgt – capitate glandular trichome, bgt- branched glandular trichome, st – stoma, pm – palisade mesophyll, sm – spongy mesophyll, tv – transcurrent vascular bundle, ph – phloem, xy - xylem, enclosed by a red oval shape is the tv showing its extension to both non-glandular and glandular trichomes. The bar represents 100µm.

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Figure 7. Freehand leaf cross section of C. ramiflora showing (a) overview of leaf and (b) vascular bundles and mesophyll tissues. Abbr.: sc – sclerenchyma, co – collenchyma, pm – palisade mesophyll, sm – spongy mesophyll, vb –vascular bundle, ph – phloem, xy - xylem, le – lower epidermis, and ue – upper epidermis. The arrow shows the embedded vascular bundle.

DISCUSSION low water availability, T. philippinensis can obtain water or moisture from its water-storing cells specifically in Results show that the leaf and stem of T. philippinensis the cortex. Roth (1984) also reported that water-storing have the characteristics typical of xerophytic plants when tissues may be developed in xeromorphic organs such compared to the anatomical structures of C. ramiflora, a as the multi-layered collenchymatous hypodermis when non-xerophytic plant. These characteristics have long been the environment conditions become complicated. The recognized as protective mechanisms of plants to survive role of collenchyma and sclerenchyma cells in stem has against adverse conditions in a particular site (Stephanou extensively been associated with mechanical support in & Manetas 1997) and as adaptive mechanisms of plants to growth and development (Leroux 2012; Qureshi et al. complete life cycle in dry environments (Atia et al. 2014). 2013). The presence of these thick simple tissues in stem First, the hypodermal layer in stem of T. philippinensis may be explained by the need to increase the strength, is remarkably thicker than that of C. ramiflora. This mechanical, and flexibility providing tissues of the species. conforms to the general differentiation of anatomical Further, the vascular structure of T. philippinensis seems structures between mesophytes and xerophytes (Roth to be directly associated with the efficient passageway of 1984). In T. philippinensis, this layer which is reinforced water and other dissolved solutes from the soil that needed by multi-layered water-storing parenchymatic tissue to be transported throughout the plant body as the tree may help the species to store water under drought grows in limestone substrate. conditions especially during summer. Well-developed Second, the characteristics of the dermal tissues of T. water-storing cells are prominent in xerophytes serving philippinensis remarkably differ from that of C. ramiflora. as special modifications to minimize the rate of water In the latter, the observed characteristics resemble the loss through transpiration. In this context, in times of typical or common anatomical structures of most vascular

265 Philippine Journal of Science Hernandez et al.: Morpho-anatomy of Tectona Vol. 145 No. 3, September 2016 philippinensis Leaf and Stem plants (e.g. mesophytes) such as some species reported mesophyll in T. philippinensis supports the anatomy of in the works of Ashton & Berlyn (1994), Rabelo et al. sun-loving plants which have long been characterized to (2012), and Qureshi et al. (2013). In the former, the wavy have longer palisade mesophyll tissues than shade plants epidermal characteristic is in conformity with what was (Ashton and Berlyn 1994; James and Bell 2000). In C. reported typical of species in the Lamiaceae family as in ramiflora, on the other hand, the structure of mesophyll the case T. grandis (Hoft 2004), T. montanum L., and T. indicates adaptation of the species to habitats which are polium L. (Dinç et al. 2011) and in the Myrtaceae species neither too dry nor too wet. Such structure suggests habitat such as Eucalyptus maculata Hook (Stocker 1960). of species that is likely to have favourable environmental Similar to plants of most Lamiaceae species and in the conditions (e.g. productive soil, high productivity, and species of Asteraceae and Solanaceae families (Maffei high diversity of both flora and fauna). Such structure 2010), the presence of trichomes is one of the most may not suggest the need to increase the photosynthetic expressed xerophytic characteristics of T. philippinensis. efficiency, storage, and mechanical support of the species Seven types of trichomes are also observed through in with respect to the prevailing environment condition (e.g. vivo leaves of T. grandis (Bandyopadhyay et al. 2004). xeric environment). Presence of these trichomes may suggest possible indicator of water requirements of T. philippinensis The vascular bundles in secondary veins of leaf are owing to the characteristics of its habitat (specifically of vertically transcurrent structure. When veins are poor soil water holding capacity) in Lobo, Batangas. As transcurrent, the parenchyma cells on either side in the remarked by Glover (2000), trichomes are prominent in vascular bundles extend all the way between the bundle water economy. Specifically, the non-glandular trichomes and the upper and lower epidermis (Metcalfe & Chalk have been extensively described as hairs providing shade 1979). Such structure has also been particularly recorded on the leaf surface to maintain a humid layer and reduce in certain Trifolieae. In some species of Caprifoliaceae, water loss through evaporation especially when stomata this structure of vascular bundles was also reported but are open. Hence, presence of trichomes in T. philippinensis the tissue surrounding the bundles and extending to both suggests low water loss through transpiration. The the adaxial and abaxial epidermis is sclerenchyma instead glandular trichomes, besides their role in water economy, of parenchyma tissues (Jakolvljevic et al. 2014). One on the other hand, have multicellular head cells which of the criteria of xeromorphy reported by Roth (1984) secrete secondary metabolites such as essential oils, is the presence of transcurrent vascular bundle, which terpenes, phenolic compounds (De & Aronne 2007), and primarily functions as supporting tissue for the entire alkaloids which have long been hypothesized to evolve mesophyll. This pattern of vascular bundle is not observed as toxic to herbivores and microbes attacking the plants in C .ramiflora which has embedded pattern of vascular (Ranger & Hower 2001; Wagner et al. 2004). bundle instead. Embedded or not transcurrent vascular bundles have long been described as characteristic of Further, important characteristics found in the leaf of non-xerophytic plant (e.g. hydrophytes and mesophytes) T. philippinensis are the hypostomatic stomata often (Roth 1984). surrounded by glandular trichomes – emerged from invaginations making the surface wavy. In most desert Moreover, remarkable is its extension to the base of both plants, these invagination structures, according to Field non-glandular and glandular hair(s) (Figure 5b). After an et al. (1998) are often blocked by trichomes which might extensive literature review, allegedly, its reporting in this further reduce transpiration. study serves as a pioneer one. This suggests a specialized support function for the entire mesophyll and enhanced Next, a study by Bezic (2003) reported the same structure storage of water and food reserves. On the upper side of of palisade tissue (Figure 6b) in the case of Spartium the leaf, non-glandular hairs may take the role of providing junceum L., a xerophyte and a well-adapted species to shade for the parenchyma cells surrounding the tvb, whose high salt concentration. This structure is also reported in primary function is to store water and starch. On the Dinarvand & Zarinkamar (2006) in the case of Ziziphus lower side of the leaf, besides reducing transpiration rate, nummularia (Burm.f.)Wight & Arn. Such structure of glandular hairs of T. philippinenis may play the role of mesophyll tissues is expressed as adaptation of plants, protecting the starch-rich storage cells from possible attack which often considered a response of plants to high light of herbivores. Such structure also suggests efficiency in intensity (Lemos-Filho 2000; Bosabalidis & Kofidis 2002) the distribution of water and reserves which need to be and defense against herbivory (Solbirg & Orians 1977). transported throughout the plant body especially during The presence of additional layer of elongated palisade drought conditions. parenchyma is also recognized as a way to increase the Lastly, the midrib of T. philippinenis also shows water use efficiency (i.e. ratio of CO2 fixed to water lost) (Lewis 1972). Furthermore, this structure of palisade possible attributes of xerophytic plant by its thick layers of collenchyma, parenchyma, and sclrenchyma

266 Philippine Journal of Science Hernandez et al.: Morpho-anatomy of Tectona Vol. 145 No. 3, September 2016 philippinensis Leaf and Stem cells (Figure 6a). These characteristics also clearly a potential to be used for forest restoration of degraded distinguish T. philippinensis from C. ramiflora. The areas in its natural habitat such as those in Batangas and latter has significantly thinner layers of simple tissues in Mindoro. It has also potential for forest rehabilitation (e.g. parenchyma cells) than that of the former. What because its anatomical structures suggest the ability has been observed in T. philippinensis is found similar to cope with various adverse conditions in the site. In to the works of Duarte & Silva (2013) and Dinarvand & northern China, for example, many of over 1,000 native Zarinkamar (2006). Xerophytes (e.g. some bryophytes) species of trees and shrubs (e.g. Pinus tabuliformis have long been characterized by having a broader lamina Carriere, Sabina chinensis L.) in the arid and semi-arid and a different structure of midrib Grebe (1912). Taken areas have extensively used for afforestation of heavily from the claim of Sack et al. (2015) on the role of much of degraded arid habitats (Bozzano et al. 2014). A number the anatomical parts of a leaf on water conductance, these of efforts in restoring arid land and biodiversity in China thick layers of parenchyma cells in midrib, consequently, reported that native shrub communities have showed may be explained by the need to increase the amount cells important ecological functions in conservation of soil, capable of storing water and food reserves. water, and biodiversity. It was also reported that native species (e.g. shrubs) are well adapted to dry soil, poor In summary, xerophytic characteristics of T. philippinensis nutrient availability, and temperature extremes (Bozzano showed structural adaptive mechanisms that are mainly et al. 2014). Further, there is this restoration effort on related to water saving and mechanical support for the saline soils in Eastern Cuba using native species, fast species. The population of T. philippinensis is reported growing exotic species and fruit trees, which reported to thrive along coastal forests, littoral cliffs and exposed that among the mixture of species, all native xerophytic limestone substrate in Lobo, Batangas, Philippines species in the area were able to survive even under severe (Caringal et al. 2015). Generally, limestone substrate heat and water stress (Bozzano et al. 2014). is characterized by having shallow or very thin soil which consists mainly of calcium carbonate. Soils As a conclusion, the anatomical structures of T. from coastal to forest zone of Lobo Watershed where philippinensis conform to the general xerophytic small population of T. philippinensis naturally grows are characteristics of the species in the Lamiaceae family generally sandy (ERDB 2003). Such soil characteristics thriving in arid or semi-arid conditions. Therefore, T. indicate low water and nutrient holding capacity and high philippinensis has the characteristics typical of xerophytic permeability. A bulk density value of less than 1.4g/m3 plants. Anatomical structures of this species suggest the is also reported as soil characteristics of habitat of the ability to survive under marginal conditions. Hence, species in Lobo, Batangas (ERDB 2003). Such value of studies on ecophysiology, pot experiments and/or field bulk density suggests that the soil is slightly compacted. trials, phenology, and associated vegetation of the species Further, the soil pH in the area is reported to be slightly are suggested to enable deeper understanding about its acidic to acidic. This means that both macronutrients habitat preference and adaptation mechanisms. and micronutrients seem to be difficult and unavailable for plants use. All these, together with the other edaphic attributes of limestone substrates as cited in Whitford (1911), make the habitat of the species a very dry one. ACKNOWLEDGMENTS Despite the condition of the habitat, population of T. The authors would like to thank the Metallophytes philippinensis is still able to outgo such conditions. More Research Laboratory of the College of Forestry and recently, the present population of the species has been Natural Resources, University of the Philippines Los reported to compose of approximately 3,000 individuals Baños for providing us the materials and equipment in across 14 barangays in Lobo, Batangas (Caringal et the conduct of anatomical examination and analysis. al. 2015). They further noted that despite the various This study also owes special thanks to the Philippine pressures and threats being faced by the species in the Tropical Forest Conservation Foundation Inc. (PTFCF) for wild, remarkably, it has a good number of regenerants. providing financial assistance for the conduct of the study. These can be attributed to its xerophytic characteristics found in leaf and stem. These characteristics have long been recognized as protective mechanisms of plants to survive against adverse conditions in a particular site REFERENCES (Stephanou & Manetas 1997) and as adaptive mechanisms AGOO MGE, OYONG GG. (2008). Assessment of of plants to complete life cycle in dry environments (Atia genetic diversity in Tectona philippinensis Benth. & et al. 2014). Hook. f., (Verbenanceae) inferred from TNRL intron Consequently, results may imply that T. philippinensis has sequences. Philippine Scientists, 45:80-89

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ASCENSA˜O L, PAIS MS. 1998. The leaf capitate DUARTE MDR, SILVA AG. 2013. Anatomical characters trichomes of Leonotis leonurus: Histochemistry, of the medicinal leaf and stem of Gymnanthemum ultrastructure and secretion. Annals of Botany amygdalinum (Delile) Sch.Bip. ex Walp. (Asteraceae). 81:263–271. Brazilian Journal of Pharmaceutical Sciences 9(4):719:727. ASHTON PMS, BERLYN GP. 1994. Leaf adaptations of some Shorea species to sun and shade. New Phytologist [ERDB] ECOSYSTEM RESEARCH AND 121: 587-596. DEVELOPMENT BUREAU. 2003. Resource Assessment, Economic Valuation and Identification of ATIA A, RAHBI M, DEBEZ A, ABDELLY C, GOUIA Rehabilitation Strategies and Alternative Livelihood H, HAOUARI C, SMAOUI A. 2014. Ecophysiological Options in Areas Within and Surrounding the Batangas aspects and photosynthetic pathways in 105 plants Bay, Philippines, Focus on Lobo Watershed (A terminal species in saline and arid environments of Tunisia. report of a funded research project by the ASEAN Journal of Arid Land 6:762–770. Regional Center for Biodiversity Conservation and AYE YY, PAMPASIT S, UMPONSTIRA C, European Union), ERDB-DENR, College Laguna 138p. THANACHAROENCHNAPHAS K, N SASAKI. FAHN A. 1964. Some anatomical adaptations in desert 2014. Floristic composition, diversity and stand plants. Phytomorphology 14:93–102. structure of tropical forests in Popa Mountain Park. Journal of Environmental Protection 5:1588-1602. FERNANDO ES, CO LL, LAGUNZAD DA, GRUÈZO WS, BARCELONA JF, MADULID DA, LAPIS AB, BANDYOPADHYAY T, GANGOPADHYAY G, TEXON GI, MANILA AC, ZAMORA PM. 2008. PODDAR R, MUKHERJEE K.K.2004. Trichomes: Threatened plants of the Philippines: a preliminary their diversity, distribution and density in acclimatization assessment. Asia Life Sciences Suppl 3:1–52. of teak (Tectona grandis L. ) plants grown in vitro. Plant Cell Tissue and Organ Culture 78:113-121. FIELD TS, ZWIENIECKI MA, DONOGHUE MJ, HOLBROOK NM. 1998. Stomatal plugs of Drimys BEZIC N, DUNKIC V, RADONIC A. 2003. Anatomical winteri (Winteraceae) protect leaves from mist but and chemical adaptation of Spartiu junceum L. in arid not drought. Proceedings of the National Academy of habitat. Acta Biologica Cravoviensia 45:43–47. Sciences 95:14256–14259. BOSABALIDIS AM, KOFIDIS. 2002. Comparative [FAO] FOOD AND AGRICULTURE ORGANIZATION. effects of drought stress on leaf anatomy of two olive 2014. Genetic Considerations in Ecosystem Restoration cultivars. Plant Science Journal 163:375-379. Using Native Tree Species. Food and Agriculture BOZZANO M, JALONEN R, THOMAS E, BOSHIER D, Organization of the United Nations: Rome. GALLO L, CAVERS S, BORDÁCS S, SMITH P, LOO GERSBACH P.V. 2002. The essential oil secretory J, eds. 2014. Genetic Considerations in Ecosystem structures of Prostanthera ovalifolia (Lamiaceae). Restoration using Native Tree Species. State of the Annals of Botany 89:255–260. World’s Forest Genetic Resources – Thematic Study. Rome, FAO and Bioversity International. GLOVER BJ. 2000. Differentiation in plant epidermal cells. Journal of Experimental Botany 51:497-505. CARINGAL AM, BUOT IE JR, ARAGONES EG JR. 2015. Population and reproductive phenology of GREBE K. 2012. Beobachtungen iiber die the Philippine teak (Tectona philippinensis Benth. Schutzvorrichtungen xerophiler Laubmoose gegen & Hook.f.) in Lobo Coast of Verde Island Passage, Trocknis. Hedwigia. Batangas, Philippines. Philippine Agricultural Scientist GYI KK, TINT K. 1998. Management status of natural 98:312–322. teak forests. In: Teak for the future. Proceedings DE MV, ARONNE G. 2007. Anatomical features, monomer of the Second Regional Seminar on Teak, Yangon, lignin composition and accumulation of phenolics in Myanmar. FAO Regional Office for Asia and the one-year-old branches of the Mediterranean Cistus Pacific, Bangkok, pp 27–48. ladanifer L. Botanical Journal of the Linnean Society HOFT M. 2004. Cross sections through the leaves of 155:361–371. several trees from a coastal wood in Kenya (Shimba DINC M, DOGU S, DOGRU KA, KAYA B. 2011. Hills National Forest) that demonstrate the variability Anatomical and nutlet differentiation between of the anatomical structure of leaves. Retrieved from Teucrium montanum and T. polium from Turkey. http://www1.biologie.uni-hamburg.de/b-online/e05/ Biologia 66:448–453. tropblat

268 Philippine Journal of Science Hernandez et al.: Morpho-anatomy of Tectona Vol. 145 No. 3, September 2016 philippinensis Leaf and Stem

HUANG S, BRUCE K, KIRCHOFF BK, LIAO J. PROTECTED AREAS AND WILDLIFE BUREAU- (2008). The capitate and peltate glandular trichomes Department of Environment and Natural Resources. of Lavandula pinnata L. (Lamiaceae): Histochemistry, 1998. The First Philippine National Report to the ultrastructure and secretion. Journal of the Torrey Convention on Biological Diversity. Protected Areas Botanical Society 135: 155–167. and Wildlife Bureau, Department of Environment and Natural. JAKOLVLJEVIC K, KUZMANOVIC N, VUKOJICIC S, LAKUSIC D. 2014. Leaf anatomical variation in RABELO GR, KELIN DE, CUNHA MD. 2012. Does Cephalaria laevigata (Dipsacaceae) under Different selective logging affect the leaf structure of a late ecologicalconditions. Archives of Biological Science successional species? Rodriguesia 63(2):419–427. doi. Belgrade 66:161–171. org/10.1590/S2175-78602012000200014. JAMES SA, BELL DT. 2000. Influence of light RANGER CM & HOWER AA. 2001. Glandular availability on leaf structure and growth of two morphology from a perennial alfalfa clone resistant to Eucalyptus globulus ssp. globulus provenances. Tree the potato leafhopper. Crop Science. 41:1427–1434. Physiology 20:1007–1018. ROTH I. 1984. Developmental aspects. Stratification JOHANSEN DA. 1940. Plant Microtechnique. Mc Graw- of tropical forest as seen in leaf structure (416-418). Hill. New York. Netherlands: Springer. LEROUX O. 2012. Collenchyma: a versatile mechanical SACK L, SCOFFONI C, JOHNSON DM, BUCKLEY TN, tissue with dynamic cell walls. Annals of Botany, BRODRIBB TJ. 2015. The anatomical determinants 110(6):1083-98. of leaf hydraulic function. In: Functional and Ecological Xylem Anatomy, HACKE U Ed. Springer KAOSA-ARD A. 1981. Teak: its natural distribution and International, Cham, Switzerland pp255–271. related factors. Natural History Bulletin Siam Society 29:55–74. SERRATO-VALENTI G, BISIO A, LORNARA C, CIARALLO G. 1997. Structural and histochemical KIYONO Y, OO MZ, OOSUMI Y, RACHMAN I. 2007. investigation of the glandular trichomes of Salvia Tree biomass of planted forests in the tropical dry aurea L. leaves and chemical analysis of the essential climatic zone: Values in the tropical dry climatic oil. Annals of Botany 79:329–336. zone of the Union of Myanmar and the eastern part of Sumba Island, Indonesia. Japan Agricultural Research SOLBRIG OT, ORIANS GH. 1977. The adaptive Quarterly 41:315–323. characteristics of desert plants. American Scientists, 65:412-421. LEMOS-FILHO JP DE. (2000). Fotoinibição em três spécies do cerrado (Annona crassifolia, Eugenia STEPHANOU M, MANETAS Y. 1997. The effects of dysenterica e Campomanesia adamantium) na estação seasons, exposure, enhanced UV-B radiation and water seca e na chuvosa. Brazilian Journal of Botany 23(1): stress on leaf epicuticular and internal UV-B absorbing 45-50. capacity of Cistus creticus: a Mediterranean field study. Journal of Experimental Botany 48:1977–1985. LEWIS MC. 1972. The physiological significance of variation in leaf structure. Science Progress 60:25–51. STOCKER O. (1960). Physiological and morphological changes in plants due to water deficiency. Arid MADULID DA., AGOO E. MG, CARINGAL AM. Zone 15–63. 2008. Tectona philippinensis. In: IUCN 2008: The IUCN Red List of Threatened Species. Version WAGNER GJ, WANG E, SHEPHERED RW. 2004. 2014.3. Retrieved November 22, 2015 from www. New approaches for studying and exploiting an old iucnredlist.org. protuberance, the plant trichome. Annals of Botany 93:3–11. MAFFEI ME. 2010. Sites of synthesis, biochemistry and functional role of plant volatiles. South African Journal WHITFORD H. N. 1911. Forests of the Philippines, Part of Botany 76:612–631. 1 & 2. Manila, Philippines: Bureau of Printing. 478p. METCALFE CR, CHALK L. 1979. Anatomy of the ZHENG B, ZHANG D, YU L. 2001. The study on the Dicotyledons, Systematic Anatomy of the leaf and developmental morphology of the glandular hairs on stem.Vol. I. 2nd Ed. Clarendon Press, Oxford. the leaf surface of Amethystea caerulea L. Journal of Natural Science 4:98–101. OZDEMIR C, SENEL G. (1999.) The Morphological, Anatomical and Karyological Properties of Salvia sclarea L. Turkish Journal of Botany 23:7–18.

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