Capsule and Seed Morphology of Commelina L. (Commelinaceae) in Relation to Taxonomy

MATERIALS AND METHODS

Capsules and seeds for the present study were obtained from fresh and herbarium samples. The voucher specimens were deposited at St. Joseph’s College herbarium (DEV). Mature and dry capsules were mounted on clean glass slides and observed under Leica MZ 7.5 Stereo zoom microscope. SEM of seeds (except C. albescens, C. appendiculata, C. coelestis and C. paleata) was taken by Hitachi su-6600. Detailed data sheets on the capsule and seed morphology were prepared by thorough observation. Capsules were drawn with Camera Lucida attached to Leica MZ 7.5 Stereo zoom microscope. The data obtained were compared and presented separately for capsule and seeds (Table 1, 2).

The terminology used for the surfaces of the seed follows Faden (1991): ventral, the surface bearing hilum; dorsal, the surface opposite the ventral; apical and basal, the surfaces facing the apex and base of capsule, respectively; lateral, the surfaces, one of which bearing the embryotega, directed towards the dorsal and ventral surfaces of the capsule. Seed length is the distance between apical and basal surfaces; width, the distances between the lateral surfaces and thickness, the distance between the ventral and dorsal surfaces. Seed shape is the linear out line viewed from the dorsal surface.

RESULTS

Commelina albescens Hassk.: Capsules 1 or 2 per spathe, ca. 4x3 mm, ovate, compressed, trilocular or bilocular, dorsal locule aborted, ventral locules 1 or 2 seeded. Seeds rounded, 2-2.5 mm, testa dull black, smooth with white farinose, hilum linear, embryotega lateral (under LM).

Specimen examined: India, Rajasthan, Jaisalmer, Dwarka, 16/10/1961, T.A.Rao 76568 (BLAT).

Table 1:	Morphological characters of the capsules of Commelina species

Table 2:	Morphological characters of the seeds of Commelina species

Commelina appendiculata C.B. Clarke: Capsule 1 or 2 per spathe, ca. 10x4.5 mm, globose, trilocular, basal ventral ovules aborted, upper ventral ovules developing into seeds, dorsal locule indehiscent. Seeds oblong, 4.5-6x2.2-2.3 mm, testa brown, smooth, appendaged at both ends, white farinose, hilum linear, embryotega lateral (under LM).

Specimens examined: India, West Bengal, Darjeeling-Jowai, 13/06/1870, C.B. Clarke 12065 (CAL). Assam, Nonpogh, Amlighat, 22/08/1964, N.P. Balakrishnan 39386 (CAL).

Commelina attenuata Vahl (Fig. IA; Plate 1A, B): Capsule 1 per spathe, ca. 4-6x3-4 mm, ovoid, bilocualr, dorsal locule aborted, ventral locules 1 seeded. Seeds elliptic, appendaged at both end, 3x1 mm, testa dark brown, smooth under LM and reticulate under SEM with farinose granules, hilum linear, embryotega lateral.

Fig. 1(A-R):	Capsules of Commelina: (A) Commelina attenuata, (B) C. benghalensis, (C) C. caroliniana, (D) C. clavata, (E) C. diffusa, (F) C. ensifolia, (G) C. forskalaei, (H) C. indehiscens, (I) C. kurzii, (J) C. longifolia, (K) C. maculata, (L) C. paludosa, (M) C. petersii, (N) C. sikkimensis, (O) C. subulata, (P) C. suffruticosa, (Q) C. tricolor and (R) C. wightii

Specimens examined: India, Kerala, Alappuzha district, Pathiramanal, 30/07/2003, Aneesha T.H.5150; Kozhikode district, Thikkodi, 30/08/2002, Santhosh Nampy and Joby 478; Thiruvananthapuram district, Veli, 11/10/2009, Sheba and Santhosh Nampy 2281 (DEV).

Commelina benghalensis L. (Fig. 1B; Plate 1C, D): Capsule 1 per spathe, 5-6x3-4 mm, oblong-elliptic, trilocular, dorsal locule 1 seeded, ventral locules 2 seeded. Seeds ovoid, 2x1.5 mm, testa black-brown, furrowed reticulate with white farinose, hilum linear, embryotega lateral.

Specimens examined: India, Kerala, Kozhikode district, Devagiri, 10/10/2001, Santhosh Nampy 141; Ambumala, 12/12/2001, Santhosh Nampy 190 (DEV). Maharashtra. Kholapur district, Ajantha Caves, 03/09/2010, Santhosh Nampy and Sheba 4280 (DEV).

Commelina caroliniana Walter (Fig. 1C; Plate 1E, F): Capsule 1 or 2 per spathe, 5-6x2-3 mm, ovate-elliptic, trilocular, dorsal locule 1 seeded, ventral locules 2 seeded. Seeds ovate-pyriform, ca. 3x2 mm, truncate at one end, sub-acute at the other end, testa dark brown, smooth, white farinose, hilum linear, embryotega lateral.

Specimens examined: India, Kerala, Wayanad district, Kabani Riverside, 30/11/2002, Joby and Santhosh Nampy 5103 (DEV). Maharashtra. Pune, Bhosari, 05/09/2010, Sheba and Santhosh Nampy 3273 (DEV). Goa. Panaji, 29/09/2002, Joby and Santhosh Nampy 841 (DEV).

Commelina clavata C.B. Clarke (Fig. 1D; Plate 1G, H): Capsule 2-3 per spathe, 8-9x4.5-6 mm, oblong-elliptic, compressed, bilocular, dorsal locule absent, ventral locules 2 seeded. Seeds elliptic, 2.5-3x2-2.2 mm, testa dark brown, shallowly reticulate, hilum linear and embryotega lateral.

Specimens examined: India, Kerala, Wayanad district, Chembra, 26/11/2003, Joby and Santhosh Nampy 874; Vythiri, 19/01/2010, Sheba and Santhosh Nampy 3214; Idukki district, Vagamon, 07/12/2010, Sheba and Shahina 4026 (DEV).

Commelina coelestis Willd.: Capsule 3 or 4 per spathe, 6-7.5x4 mm, oblong, trilocular, dorsal locule 1 seeded, ventral locules 2 seeded. Seeds triangular, ca. 3.4x2.3 mm, testa brown or black, pitted, hilum linear, embryotega lateral (under LM).

Specimens examined: India, Tamil Nadu, Nilgiri, Ootty, 07/1883, unknown s.n (MH); Sikkim, 13/08/1875, G. King 2239 (CAL).

Commelina diffusa Burm.f. (Fig. 1E; Plate 2A, B): Capsule 1-3 per spathe, 8-9x4-5 mm, oblong, trilocular, dorsal locule 1 seeded, ventral locules 2 seeded. Seeds oblong, ca. 4x2 mm, testa brown, doubly reticulate, hilum linear, embryotega lateral.

Specimens examined: India, Kerala, Kozhikode district, Palazhi, 12/02/2003, Joby and Aneesha 95; Thamarassery, 18/07/2010, Sheba and Santhosh Nampy 3240 (DEV). Meghalaya. Way to Jowai, 09/09/2009, Sheba and Santhosh Nampy 2275 (DEV).

Commelina ensifolia R. Br. (Fig. 1F; Plate 2C, D): Capsule 1-2 per spathe, 5-6x4-5 mm, elliptic-obovoid, bi or trilocular, rarely dorsal locule absent, ventral locules 1 seeded. Seeds ovoid, 2.5-3.5x2-3 mm, testa mottled light and dark brown, smooth under LM and coarsely reticulate under SEM, a torus of soft whitish brown material around the periphery, hilum linear, embryotega lateral.

Specimens examined: India, Kerala, Thiruvananthapuram district, Museum, 05/11/2010, Sheba and Santhosh Nampy 4006; Kozhikode district, Devagiri Botanical garden, 04/06/2010, Sheba and Santhosh Nampy 3234 (DEV). Tamil Nadu. Nilgiri, Naduvattom, 20/11/01, Santhosh Nampy 177 (DEV).

Commelina forskalaei Vahl (Fig. 1G; Plate 2E, F): Capsule 1 per spathe, 5-6x3.5-4 mm, obovoid, trilocular, dorsal locule 1 seeded ventral locule 2 seeded. Seeds globose, ca. 2.5x2 mm, testa brown, smooth under LM and coarsely reticulate under SEM, hilum linear, embryotega lateral. Capsules of cleistogamous flowers 1 or 2 seeded, indehiscent. Seeds smooth with furrows and ridges.

Specimens examined: India, Kerala, Kozhikode district, Nandi, 03/08/2002, Joby and Santhosh Nampy 483 (DEV). Karnataka. Mysore, 04/10/2001, Santhosh Nampy 138; 06/06/2010, Sheba and Santhosh Nampy 3235 (DEV).

Commelina indehiscens E. Barnes (Fig. 1H; Plate 2G, H): Capsules 1-3 per spathe, 1-1.2x0.3-0.4 cm, oblong, trilocular, indehiscent, laterally compressed, dorsal locule 1 seeded, ventral locules aborted. Seeds ovoid, 6.5x2 mm, testa black-dark brown with light brown reticulations, hilum linear, embryotega lateral.

plate. 1:	(A-B) Commelina attenuata Vahl., (C-D) C. benghalensis L., (E-F) C. caroliniana Walter, (G-H) C. clavata C.B. Clarke

Plate 2::	(A-B) Commelina diffusa Burm.f., (C-D) C. ensifolia R. Br., (E-F) C.forskalaei Vahl, (G-H) C. indehiscens E. Barnes

Plate 3:	(A-B) Commelina kurzii C.B. C larke, (C-D) C. longifolia Lam., ( E-F) C. maculata Edgew., (G-H) C. paludosa Blume

Plate 4:	(A-B) Commelina petersii Hassk., (C-D) C. sikkimensis C. B. Clarke, (E-F) C. subulata Roth, (G-H) C. suffruticosa Blume

Plate 5:	(A-B) Commelina tricolor E. Barnes, (C-D) C. wightii R.S. Rao

Specimens examined: India, Kerala, Idukki district, Adimali, 19/11/2010, Sheba and Santhosh Nampy 4015, Wayanad district, Ambalavayal, 20/06/2009, Sheba and Santhosh Nampy 3205 (DEV).

Commelina kurzii C. B. Clarke (Fig. 1I; Plate 3A, B): Capsule 1 or 2 per spathe, 7-8x5-6 mm, globose, trilocular, locules 1 seeded, rarely dorsal locule aborted. Seeds ovate, ca. 3x2 mm, testa brown, smooth, torus of brown material around the periphery, hilum linear, embryotega lateral.

Specimens examined: India, Kerala, Thrissur district, Vazhani forest, 15/08/2003, Aneesha and Joby 939; Wadakkancherry, 10/12/2010, Shahina and Sheba 4050; Palakkadu district, Nelliyampathy, 12/12/2002, Joby and Santhosh Nampy 5115 (DEV). Tamil Nadu, Tirunelvely, Courtallum, 11/09/2003, Joby and Santhosh Nampy 969 (DEV).

Commelina longifolia Lam. (Fig. 1J; Plate 3C, D): Capsule 1or 2 per spathe, 8-9x3-4 mm, oblong, trilocular, dorsal locule 1 seeded, ventral locules 2 seeded. Seeds ovoid, ca.3x2 mm, testa brown, smooth with white farinose, whitish appendage at the rounded end, hilum linear, embryotega lateral.

Specimen examined: India, Maharashtra, Pune, Nigdi, 03/09/2010, Sheba and Santhosh Nampy 3264 (DEV).

Commelina maculata Edgew. (Fig. 1K; Plate 3E, F): Capsule 1 or 2 per spathe, 6-7x5 mm, ovoid, trilocular, locules 1 seeded. Seeds oblong, ca. 3x2 mm, testa reddish brown, smooth, hilum linear, embryotega lateral.

Specimens examined: India, Meghalaya, Shillong, Moplangh, 08/09/2009, Sheba and Santhosh Nampy 2269; Shillong, 08/09/2009, Sheba and Santhosh Nampy 2266, 2267 (DEV).

Commelina paleata Hassk.: Capsule 1 or 2 per spathe, ca. 6x4 mm, oblong, trilocular, locules 1-seeded. Seeds oblong, 3x1 mm, testa dark brown, smooth with white farinose, hilum linear, embryotega lateral (Under LM).

Specimen examined: India, Maharashtra, Thane, Vander-odi, 19/09/1968, K.V. Billore 116770 (CAL). Tamil Nadu, Salem, Hogainakkal, 12/07/1964, E. Vajravelu 20580 (MH).

Commelina paludosa Blume (Fig. 1L; Plate 3G, H): Capsule 1-3 per spathe, 4x3 mm, obovoid, trilocular, locules equal, 1 seeded. Seeds ellipsoid, 3-4x2.5 mm, testa dark brown, smooth under LM and coarsely reticulate under SEM, minutely white farinose, hilum linear, embryotega lateral.

Specimens examined: India, Kerala, Kannur district, Kottiyoor, 01/10/2003, Joby and Santhosh Nampy 998; Kozhikode, district, Devagiri Botanical Garden, 03/01/2011, Sheba and Santhosh Nampy 4035; Muthappanpuzha, 25/02/2001, Santhosh Nampy 566; Ambumala, 12/12/2001, Santhosh Nampy 186 (DEV).

Commelina petersii Hassk. (Fig. 1M; Plate 4A, B): Capsule 1 or 2 per spathe, 9-10x3-4 mm, ovate elliptic, compressed, trilocular or bilocular, dorsal locule 1 seeded, rarely absent, ventral locules 2 seeded. Seeds ovate-pyriform, 1.75x1 mm, testa dark brown, mottled with black, 3-6 transverse furrows, the intervening ridges with 2-many white-light brown tubercles, hilum linear, embryotega lateral.

Specimens examined: Kerala. Kozhikode district, Devagiri Botanical Garden, 07/06/2009, Sheba and Santhosh Nampy 3201 (DEV). Tamil Nadu. Coimbatore, 27/11/2010, Sheba and Santhosh Nampy 3973; Gudallur, 20/11/2001, Santhosh Nampy 580 (DEV).

Commelina sikkimensis C.B. Clarke (Fig. 1N; Plate 4C, D): Capsule 1 or 2 per spathe, 5-6x2-3 mm, oblong, trilocular, dorsal locule 1 seeded, ventral locules 2 seeded. Seeds ovoid-oblong, 3-4x2-3 mm, testa dark brown, reticulately pitted, hilum linear, embryotega lateral.

Specimens examined: India, Meghalaya, Jowai, 09/09/2009, Sheba and Santhosh Nampy 2271, 2276 (DEV).

Commelina subulata Roth (Fig. 1O; Plate 4E, F): Capsule 2 per spathe, 4.5x2.5 mm, oblong, trilocular, dorsal locule 1 seeded, ventral locules 2 seeded. Seeds ovoid, compressed, ca. 2 mm, testa black, transversely pitted, white farinose, hilum linear, embryotega lateral.

Specimen examined: India, Andhra Pradesh, Chitoor district, Horsely hill, 19/10/2004, Joby and Ratheesh 1152 (DEV).

Commelina suffruticosa Blume (Fig. 1P; Plate 4G, H): Capsule 5 or 6 per spathe, ca. 5x5 mm, globose, trilocular, dorsal locule aborted, ventral locules 1 seeded. Seeds elliptic 3x2 mm, testa dark brown, foveate reticulate, white farinose, hilum linear, embryotega lateral.

Specimens examined: India, Kerala, Pathanamthitta district, Elimullu, 31/05/2010, Sheba and Santhosh Nampy 3232; Thrissur district, Athirappally, 16/08/2003, Aneesha and Joby 946; Wayanad district, Muthanga, 25/08/2002, Dineshraj and Santhosh Nampy 824 (DEV).

Commelina tricolor E. Barnes (Fig. 1Q; Plate 5A, B): Capsule 1or 2 per spathe, 9-10x3-3.5 mm, ovoid-oblong, compressed, bilocular, dorsal locule absent, ventral locules 2 seeded. Seeds ovoid-oblong, 4x1.5 mm, testa pale brown, smooth with farinose granules, hilum linear, embryotega lateral.

Specimens examined: India, Kerala. Wayanad district, Muthanga, 29/11/2002, Joby and Santhosh Nampy 891(DEV). Tamil Nadu. Needle point, 06/10/2002, Nisha and Dineshraj 847; 25/10/2003, Joby and Santhosh Nampy 5178; 26/09/2010, Sheba and Santhosh Nampy 3485 (DEV).

Commelina wightii R.S. Rao (Fig. 1R; Plate 5C, D): Capsule 1 per spathe, 5-5.5x3.5-4 mm, globose, dorsal locule and 1 ventral locule aborted, 1 ventral locule 1 seeded. Seed globose, 2x2 mm, testa brown, smooth under LM, coarsely reticulate under SEM, hilum linear, embryotega lateral.

Specimen examined: India, Kerala, Kozhikode district, Devagiri Botanical Garden, 27/10/2010, Sheba and Santhosh Nampy 3292; Thrissur district, Brahmakulam, 09/08/2010, Alfred and Shahina 3253 (DEV).

DISCUSSION

The capsule and seed morphology of 22 Indian species Commelina are investigated. They provide taxonomically useful characters for species delimitation.

The size of the capsule varies from 4-10x2-6 mm. The longest capsule is found in C. appendiculata and C. indehiscens and the smallest in C. subulata. The tip of the capsule is long and pointed in C. indehiscens.

The shape of the capsule varies from globose, ovoid, obovoid, oblong to elliptic. Globose capsules are found in C. kurzii, C. wightii, C. appendiculata and C. suffruticosa. In C. albescens, C. maculata and C. attenuata, the capsules are ovoid while in C. paludosa and C. forskalaei the capsules are obovoid. Capsules are ovate-elliptic in C. petersii and C. caroliniana but in C. clavata, it is oblong-elliptic. It is obovoid elliptic in C. ensifolia and ovoid-oblong in C. tricolor. All the others are with oblong capsule.

The capsules are either 1 or 2 within a spathe generally but it is always one in C. attenuata, C. benghalensis, C. forskalaei and C. wightii. It is always two in C. subulata, 3 or 4 in C. coelestis and 5 or 6 in C. suffruticosa.

The capsule is trilocular in most species, but it is bilocular in C. clavata, C. suffruticosa, C. tricolor and C. attenuata. Only one locule is functional in C. wightii due to the abortion of the dorsal and one of the ventral locule. In C. kurzii, C. ensifolia, C. petersii and C. albescens, the second flower produces bilocular capsule.

The two ventral locules are 2 seeded usually, but they are aborted in C. indehiscens. In C. wightii one of the ventral locule is aborted while the other is 1 seeded. In C. ensifolia, C. maculata, C. paludosa, C. suffruticosa, C. kurzii, C. appendiculata and C. paleata the ventral locules are always one seeded.

The size of the seeds varies from 2-6x1-3 mm. Largest seed is in C. appendiculata and C. indehiscens and the smallest seed is found in C. subulata.

The seed also shows variation in shape, size, number, colour of the testa and ornamentation. The seed is triangular in C. coelestis, ovoid-oblong in C. sikkimensis and C. tricolor, globular in C. forskalaei, C. wightii and C. albescens, elliptic in C. attenuata, C. suffruticosa, C. paludosa and C. clavata, ovoid in C. benghalensis, C. ensifolia, C. indehiscens, C. longifolia, C. subulata and C. kurzii, oblong in C. diffusa, C. maculata and C. paleata and ovate-pyriform in C. caroliniana and C. petersii.

The ornamentation of the seed surface under LM is smooth, reticulate, pitted or ridged. At SEM, the surface is granulate, rugulate, reticulate or perforate with or without farinose granules. The surface is irregularly pitted in C. coelestis, transversely pitted in C. subulata, reticulately pitted in C. sikkimensis. In C. petersii the surface with tubercles on ridges and in C. benghalensis shows furrowed reticulations. The seed of C. suffruticosa is foveoate reticulate, C. clavata is shallowly reticulate and C. diffusa is doubly reticulate. In all the other species the surface is smooth.

Farinose granules are absent in C. coelestis, C. kurzii, C. wightii, C. sikkimensis, C. indehiscens, C. forskalaei, C. clavata and C. petersii. In all others, the farinose granules are scattered in different manner. It may be thickly arranged or irregularly scattered. Comparatively larger farinose outgrowths are seen in C. ensifolia, C. maculata C. paludosa and C. suffruticosa.

The seeds are appendaged at both ends in C. appendiculata and C. attenuata and single appendaged in C. longifolia. The appendages are honey comb like in C. attenuata. Tubercles are found through the ridges in C. petersii. In all Indian species studied, the hilum is linear and the embryotega is lateral.

KEY TO THE SPECIES

ACKNOWLEDGMENTS

The authors are grateful to Dr. C.J. Mani, Head, Department of Botany and Principal, St. Joseph’s College, Devagiri, Kozhikode-8 for facilities. The authors are also thankful to Mr. Manudev K.M. for illustration. One of us (SMJ) is thankful to UGC, New Delhi for awarding FIP and Principal, St. Mary’s College, Sulthan Bathery for permitting to take up the Teacher Fellowship.