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The stem- node- leaf anatomy of Boswellia serrata shows that the vascular bundles(traces) depart from the internode and enter into the node as three traces showing trilacunar three trace condition, anastomosing at the petiole base, travelled in rachis to respective alternate and terminal leaflets. Gum-resin ducts were observed.

In this paper the stem- node- leaf continuum is described in Boswellia serrata.

Sinnott (1914) stated that foliar nodes in angiosperms vis. unilacunar ,trilacunar and multilacunar. The trilacunar is primitive and uni and multilacunar one derived from it. The further nodal anatomy were studied by Sharma et al (2009) in Asteraceae ; khorwal and Sharma  (2011) in Indigofera linnaei ;kshirsagar(2016) in Woodfordiu fruticosa, Cuphea ignea and Lawsonia inermis L (Lgthraceae); jain(1977) 32sp.of Bignoniacae, Aswale and sutar (2021)17genra of Bignoniaceae. Unilacunar one, three and multitraced condition, Mitra et al (2015) studied comperative nodal and petiolar anatomy of 16 species of Sterculiaceae. Howard(1974)postulated the trilacunar three trace condition its importance in classification,Howard(1963)categarised the petiolar structure into different types.

Bangar (2021)studied nodal anatomy of Petrea volubilis L. Verfenacoae (umilacuner one traced).

Samples of fresh plant material 3-4 nodes below the apex of twig in the month of April were collected and preserved in FAA solution, dehydrated in TBA series, embedded in paraffin wax, serial transverse sections of internode, node, petiole, rachis up to terminal leaflet were cut at 8-15µm, dewaxinated in xylol, sections were passed through ethyl alcohol down and up series, stained with safranin and light green solutions. Photographs were taken from Nikons Camera.

Boswellia serrata is a medium sized tree plant belongs to the family Brusuaceae,stem much branched, round to ovate, hairy, green, Oliogum-resin seen  on the stem, crown of leaves at twig apex, leaves are alternate unipinnately compound,15cm to 50cm long on mature branches, phyllotaxy is1/5, leaflets are subopposite on the rachis, 6-18 pairs, subpetiolulelate, ovate to oblong shaped, serrate, apex rounded of base leaflets while accute  progressively up to terminal ones, size ranges 1.6cmto 4.5cm,length and 1.5cm to 1.7 cm width. It is prevalent in forest area of Aravali hills ranges situated in Thanagazi, Alwar, Rajasthan (Fig.13, 14). Its gum-resin products are medicinally important. It is also known as Indian frankincense. 

The internode anatomy(Fig.1.) shows round ovate periphery, its transverse sections show the following anatomical structures:

Epidermis-single layered parenchymatous, rounded to ovate in shape some cells are papiliate, thick cuiticle present, multicellular uniseriate hairs are present.

Hypodermis-2to3 layered, parenchymatous, large sized cells filled with tannin.

Cortex-8to10 layered, parenchymatous, small intercellular spaces are present, cells are filled with tannin.

Pericycle- heterogeneous, sclerachymaous interrupted with parenchymatous tissue,resin canal are present.

Vascular bundles- Conjoint colletral, arranged in ring, vascular tissues i.e. Phloem and xylem are continous. The xylem parenchyma bears the resin canals and some tannin cells.

Pith –the huge internal area of internode covered with pith. The cells are parenchymatous penta to hexagonal , large number of cells are filled with tanin showing brown coloured cells.

Nodal  and leaf anatomy - nodal anatomy shows trilacunar three trace condition of which the median trace (MT) is larger in size . The lateral traces(LT₁,LT₂)(Fig.2) separates first from vascular cylinder leaving the leaf trace gaps(LTG)(Fig.2,3,4). The lateral gapes closed earlier than median gap the lateral traces (LT1,LT₂) moves into cortex towards to median trace (MT) (Fig.3,4) simultanious median trace gap closed. The all three traces (LT₁,LT₂and MT)(FIG.4) start to fuse at the entry base of leaf petiole. TheyLT₁,LT₂,MT) anastomosed and forming a vascular cylinder(VB)(Fig.5) at the petiole further enters into rachis with later laterally vascular supply to the leaflets alternately further  the second leaflet pair received vasculature from  the rachis.

The present study supports to the Howard (1963,1974) trilacunar three trace  and petiolar anatomy.

Figures 1-4

1. Showing internode vasculature and anatomy, outward migration of leaf traces.

2. Showing the leaf traces LT₁, LT₂, MT travelled in cortical region.

3. Leaf traces (LT₁, LT₂, MT) at the petiole base and leaf trace gaps.

4. Anastomosised all the traces.

Figures 5-8

1. Showing vasculature and anatomy of petiole.

2. Showing the migration of vascular bundles in leaflet.

3. Showing rachis vasculature and its anatomy.

4. Supply of vascular bundles in second leaflet.

FIGURES 9-12

1. Showing vasculature, anatomy and resin canal of rachis after second leaflet.

2. Showing vascular supply in next leaflets progressively.

3. Showing vasculature and anatomy of rachis and termination into last leaflet petiolule vasculature, presence of resin canal, tannin cell.

4. Showing vasculature to terminating leaflet.

5. Tree of Boswellia serrata.

6. Twig showing phyllotaxy and arrangement of leaflets

LT1=Lateral leaf trace first, LT2=Lateral leaf trace second, LTG=Leaf trace gap, MT=Median leaf trace RC= Resin canal, TC= Tannin cell, PI=Pith, PH= Phloem, XY= Xylem, E= Epidermis, H=Hair, VB= Vascular bundles, LL= Leaflet, HY= Hypodermis, LLV= Leaflet vasculature, LLVC= Leaflet vasculature cylinder.

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