Comparative anatomical studies for three species of the genus convolvulus دراسة تشريحية مقارنة لثلاثة أنواع من جنس العليق

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J. Coli. Sci., King Saud Univ. 13 (\), pp. 81-96 (I982)

Comparative Anatomical Studies Species of the Genus Convolvulus

for Three

Abdullah R. Doaigey, Mohammed I. Mady, and Hesham A. Gawad

Botany Department,College oj Science. King Saud University Riyadh, Saudi Arabia.

This anatomical study deals with the following three species of Con volvulus:

(I) Convolvulus arvensis. L.

(2)

c.

^Lana/us^Yah!.

(3) c. pros/ra/us Forssk.

Transverse sections of the stems indicate that cortex of species (I) and (2) contains chlorenchyma and parenchyma cells while that of species (3) contains only chlorenchyma cells. AU three species have interxylary phloem. Pith appears homogenous in all three species except the presence of what appears to be secretary canals in pith of species (2) which appears also in the stem of species (I) and (3) in association with outer phloem.

Transverse sections of the leaves show that upper and lower palisade tissue, 3 or 4 layers in thickness, is present in all species forming a continuous zone in species (2) but discontinuous at the midrib in species (J) and (3). Species (I) has collenchyma cells located next to the upper epidermis in the midrib. This supporting tissue is absent from the other species.

Eglandular trichomes are present on the stem and leaves of species (2) and (3) but absent on species (I). Glandular trichomes are only observed on the stem and leaves of species (I). Cuticle of stems and leaves of all species is irregularly striated.

Convolvulus L., a member of Convolvalaceae, is of creeping or twining perennial herbs or shrubs of different appearance and habit; leaves simple or lobed; flowers with five funnel-shaped corolla of irregular coloured strips (Migahid, 1978).

Anatomical characteristics of some members of this genus indicate that the epidermal cells are characterized by sinuous anticlinal walls (Esau, 1965);

trichomes are eglandular commonly two-armed shaped (Metcalfe and Chalk,

81

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82 A.R.Doaigey, M.I.Mady and H.A.Gawad

1950); stem cortex contains chlorenchyma with laticiferous canals and secretory cells (Sabins, 1921; Metcalfe and Chalk, 1950; and Esau, 1965); vascular bundles possessing interxylary phloem and the xylem forms an almost closed vascular cylinder with narrow rays (Maire, 1913; and Metcalfe and Chalk, 1950); outer phloem exhibits the presence of sclereids in the outer region (Sabins, 1921); vessels indicate the occurrence of tylosis (Earns and Mac Danieles, 1953).

^arvel/sisthrives near cultivated land, which has also been reported by Polunin and Huxley (J 972), while C lanaI liS and C {Jro.~/raIIiS are found in their natural desert habitat among other members of the Flora.

Material and Methods

Plants were collected during the flowering season of 1979 from Riyadh area, Saudi Arabia. Materials were immediately preserved in ethanol, 70%. Surface preparations were made from the leaves and stems by stripping the epidermis and were then mounted in glycerol solution, 50% (v Iv). Leaves were occassionally cleared in chloral hydrate solution and subsequently mounted in glycerol solution, 50% (v Iv). Sections were prepared by Rotary microtomy (20-30 ~), stained in safranin and light green and then mounted in Canada balsam for making the drawings. Some sections were mounted in phlorogycerol solution and hydrochloric acid when examined for lignified elements, or mounted in iodine solution to test for the presence of starch. Drawings have been made by the aid of Reichert screen microprojector.

A. Epidermal characters Leaves

Results 1)

e.

^arvensis

Intercostal region, upper epidermis: cells regular with sinuous anticlinal walls;

cuticle thin, irregularly striated; stomata frequent, ovate, paracytic although occasionally anisocytic; occasional glandular trichomes have unicellular stalk and multicellular large head (Fig. loB, Fig. 2-D & E).

Intercostal region, lower epidermis: epidermal cells, cuticle layer, trichomes, and stomata are similar to those of the intercostal upper epidermis (Fig. I-D).

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Comparative Anatomical Studies for Three Species of Convolvulus 83

Midrib, upper epidermis: cells elongated with slightly sinuous anticlinal walls:

cuticle thin, longitudinally striated (Fig. I-A): stomata infrequent, ovate, mainly paracytic occasionally anisocytic; occasional glandular trichomes similar to those of upper epidermis of intercostal region (Fig. 2-D & E).

Midrib, lower epidermis: epidermal cells, cuticle layer, stomata, and trichomes are similar to those of the upper epidermis of the midrib (Fig. I-C).

Siems:

Epidermis: cells elongated, with straight anticlinal walls: cuticle thin, irregularly striated; stomata frequent, ovate and paracytic (Fig. 2-A); glandular trichomes occasional unicellular stalks and multicellular heads (Fig. 2-D & E).

B. Inlernal Siruciure Leaves

Inlercoslal region: palisade tissue below both epidermises, 3 or 4 layers of elongated cells containing chloroplasts, with conspicuous intercellular spaces;

secretory structure represented by large cells, located in the spongy tissue (Fig. I-E

& G).

Midrib region: spongy tissue of single layer at the abaxial side; palisade tissue abscent; lacunar collenchyma tissue of 2 or 3 layers at the adaxial side; abaxial phloem present (Fig. 1- F & G).

Siems

Corlex: outer region of chlorenchyma, 3 or 4 layers; inner region of parenchyma, 3 to 6 layers some tangentially elongated, conspicuous intercellular spaces.

Endodermis: absence of starch. Vascular lissue: inner phloem present; vessels wide.

Medulla: large, unlignified parenchymatous cells, conspicuous intercellular spaces.

Secrelory slruclure: present, located in the outer phloem (Fig. 2- B & C).

A - Epidermal Characlers Leaves

2) C. lanai us

Inlercoslal region, upper epidermis: cells with straight anticlinal walls; cuticle thin, irregularly striated; stomata· frequent, ovate, paracytic; abundant, unicellular, unbranched covering trichomes with lignified walls, acute apices and swollen bases (Fig. 3-A).

Inlercoslal region, lower epidermis: cells, cuticle, stomata, and trichomes similar to those of upper epidennis (Fig. 3-C).

Midrib, upper epidermis: elongated cells with straight anticlinal walls; cuticle thin, longitudinally striated (Fig. 3-B); stomata occasionally present and covering trichomes occur frequently, both similar to those of the upper epidermis of the intercostal region.

Midrib, lower epidermis: cells, cuticle, stomata, and trichomes similar to those of the upper epidermis of the midrib.

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84 A.R.Ooaigey, M.I.Mady and H.A.Gawad

Stems

Epidermal cells elongated with straight anticlinal walls; cuticle thin, irregularly striated; stomata frequent, ovate, paracytic; covering trichomes abundant, unicellular with thick lignified walls, having acute apices and swollen bases (Fig.

4-A).

B. Internal Structures Leaves

Intercostal region: Palisade tissue below both epidermises, 2 or 3 layers of elongated cells containing chloroplasts, with conspicuous intercellular spaces;

spongy tissue of 2 or 3 layers of irregular cells with chloroplasts, conspicuous intercellular spaces; secretory structure located in the spongy mesophyll tissue, represented by schizogenous intercellular spaces (Fig. 3-D & F).

Midrib region: Palisade tissue below both epidermises, 2 or 3 layers of elongated cells containing chloroplasts, with conspicuous intercellular spaces; spongy and collenchyma tissues absent; parenchymatous tissue 5 or 6 layers, irregular cells, below both palisade tissues; abaxial phloem present; secretory structures present in the parenchymatous tissue at the abaxial side (Fig. 3-E & F).

Stems

Cortex: radially enlongated chlorenchyma cells, 3 or 4 layers below epidermis;

parenchyma 3 or 4 layers of cells mostly tangentially elongated; inner phloem present; medulla of small, unlignified parenchymatous cells, with conspicuous intercellular spaces; schizogenous secretory structures present in the medulla (Fig.

4-B & C).

A. Epidermal characters Leaves

3} C. Prostratus

Intercostal region, upper epidermis: cells with slightly sinuous anticlinal walls;

cuticle thin, irregular striated; stomata frequent, ovate, commonly anomocytic, occasionally anisocytic; frequent, unicellular, unbranched covering trichomes, with lignified walls, acute apices and swollen bases (Fig. 5-B).

Intercostal region, lower epidermis: cells, cuticle stomata, and covering trichomes similar to those of the upper epidermis of the intercostal region (Fig. 5-D).

Midrib, upper epidermis: elongated cells with slightly sinuous anticlinal walls;

cuticle thin longitudinally striated (Fig. 5-A); stomata infrequent and covering trichomes frequent, both similar to those of upper epidermis of the intercostal region (Fig. 5-B).

Midrib, lower epidermis: cells, cuticle, stomata, and covering trichomes similar to those of upper epidermis of the midrib.

Stems

Epidermal cells elongated with straight anti clinical walls; cuticle thin, irregularly

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Comparative Anatomical Studies for Three Species of Convolvulu.! 85

striated; stomata frequent, ovate, and anomocytic; frequent, unicellular, unbranched covering trichomes with thick lignified walls, acute apices swollen bases (Fig. 6-A).

B. Inlernal SI rucl ures Leaves

Inlercoslal region: Palisade tissue below both epidermises, 2 or 3 layers of elongated cells containing chloroplasts, with conspicuous intercellular spaces;

spongy tissue 2 to 4 layers of irregular cells containing chloroplasts, with conspicuous intercellular spaces; secretory structures frequent, located in the spongy mesophyll, represented by schizogenous intercellular spaces (Fig. 5-C & F).

Midrib region: Palisade tissue only below the epidermis of the abaxial side, 2 or 3 layers of elongated cells containing chloroplasts, with conspicuous intercellular spaces; parenchymatous tissue present below the upper epidermis and below the palisade tissue at the abaxial side, 2 to 4 layers; abaxial phloem present (Fig. 5-E &

F).

Siems

Cortex: radially elongated chlorenchymatous cells, 3 or 4 layers below epidermis, prominent one layer of tangentially elongated cells of endodermis devoid of starch; a group of unlignified, thick walled fibres present at the outer region of outer phloem; inner phloem present; medulla unlignified parenchymatous cells, small on the periphery and large in the center, with conspicuous intercellular spaces; secretory structures present in the outer phloem (Fig. 6-B & C).

Discussion

It is evident that these three species have several characteristics in common, however, they differ in many others. Thus, the cuticle of the stems and the intercostal region of the leaves of all three species is irregularly striated, although that of the midrib region is longitudinally striated. Stomata are consistently ovately shaped. In addition it was judged to be frequently occurring on the stem and on the intercostal region of the leaves of all three species. As far as the stomatal type is concerned ,the anomocytic type occurs solely on C. proslralUS, while paracytic stomata occur on both

c.

arvensis and C. lana/us. However, this relationship is not a simple one since stomata of the anisocytic type occur on both

c.

^arvensisand C.

proslralUS. Epidermal cells of the stems of the three species and of the leaves of C.

lana/us are characterized by straight anticlinal walls, although those of the leaves of the other two species have sinuous or slightly sinuous anticlinal walls. Epidermal trichomes are present on the leaves and stems of all the species. However, they are different not only in their distribution, but also in their type. Trichomes only occasionally occur on the leaves and stems of C. arvensis, while they are more frequently distributed on C. pros/ra/us and abundantly present on C. lanai us. The stems of these species have been described as being, in order, glabrous, villous, and wooly (Migahid, 1978). Perhaps the types trichomes present may also contribute to

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86 A.R. Doaigey, M.I. Mady and H.A. Gawad

this morphological appearance since C. arvensis has short multicellular glandular trichomes, less than 50 ^J..I. in length, while C. pros/rafUs and C. lana/us have long unicellular unbranched covering trichomes, 250 to 600 ^J..I. in length.

The internal structure of the intercostal region of the leaves of the three species is quite similar. It is characterized by the presence of adaxial and abaxial palisade tissues and spongy tissue located in between. This similarity extends also to the presence of secretory structures and to their localization in the spongy tissue.

However, these species are dissimilar in the type of secretory structure present. It is the cellular type in C. arvensis, while in C. lana/us and C. pros/ra/us it is of the schizogenous type.

By comparing the internal characteristics of the midrib region, it becomes clear that, with the exception of the presence of abaxial phloem, nothing else unifies

. these three species. However, C. lana/us and C. pros/ra/us have many

characteristics in common, the odd one being C. arvellsis. For instance, only C.

arvensis possesses supportive tissue of collenchyma cells. In addition, the chlorenchyma-type, photosynthetic tissues present are different in distribution and in cellular shape among the three species. In C. arvensis, it is made of a single layer of irregularly shaped celis located only at the abaxial side. In C. pros/rafUS, it is made of 2 to 4 layers of palisade mesophyll cells located only at the abaxial side.

However, in C.lana/us, it is made of palisade mesophyll tissues located at both the . abaxial and adaxial sides, each consists of 2 or 3 layers of cells.

The internal characteristics of the stems of these three species, although similar, are not exactly the same. Thus, while the outer region of the cortex consists of 3 or 4 layers of chlorenchymatous cells in all three species, it is nervetheless different in appearance. These cells, as appearing in transverse sections, are small and isodiametric in C. arvensis, while they are radially elongated in C. lana/us and C.

pros I railis. The inner region of the cortex is similar in both. C. an'(!/Isis and C. lallalliS

and is made of several layers of tangentially elongated parenchymatous cells. It is reduced to a single prominent layer of endodermis in C. pros/ra/u.s. The similarity in the anatomical features of the stems of these species extends to tbe presence of interxylary phloem,a fact that has been reported before by Maire(1913).However C.

pros/ra/us stands alone by possessing unlignified fibres in the interxylary phloem.

This is in agreement with the findings of Sabins (I 921) on the same species, then known as C. microphyllous. The medulla of these three species is uniformly unlignified, a feature that is shared also with C.jloridus. The findings on C.jloridus

have been reported by Metcalfe and Chalk (I 950). Secretory structures are present in the stems of the three species. This has also been reported for C. jloridus

(Metcalfe and Chalk, 1950) and has been suggested as characteristic of the genus

('OI11'o/l'II/I1S by Esau (965). However, there are variations in the localization of the secretory structures in the sterns of the three species. These structures are present in the medulla of C. lana/liS although they are associated with the outer phloem of C. arvensis and C. pros/rafUS.

The foregoing discussion indicates that these three species have some characteristics in common which may be suggested as anatomical features for the

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Comparative Anatomical Studies for Three Species of Con volvulus 87

genus Convolvulus (Table I). However, these species may be recognized as separate species based on some anatomical characters that set them apart. In the meantime, some of these 'characters show a closer relationship between C. lanatus and C.

prost rat us. This is illustrated in Table I.

A bbrevia 1 ions

abo phi, abaxial phloem; ad. phi, adaxial phloem; ch, chloroplasts; cic, cicatrix; col, colienchyma; C. par, cortical parenchyma; cut, cuticle; end, endodermis, ep, epidermis; g, glandular trichome; I.e, lower epidermis; m, medulla; pal, palisade; par, parechyma; phi, phloem; phI. f, outer phloem fibres; p. phi, perimedullary phloem; sp. m, spongy mesophyli; s.st, secretory structure; st, stomata; str, cuticular striations; u.e, upper epidermis; v.b, vascular bundle; xy, xylem; xy. r, xylem ray.

Rererences

Eams, A.J. and MacDanleles, L. H. (1953) An Inlroducfion 10 Planl Analomy. McGraw·Hill Book. Company, Inc., New York..

Esau, K. (1965) Plam A nalomy. 2nd ed. John Wiley & Sons, Inc., New York..

Maire, R.C. (1913) Un nouveau Convolvulus. A Igerian Bull. Soc. Bot. 60, 253-256.

Metcalfe, C.R. and Chalk, L. (1950). Anatomy oj the Dicotyledons. Vol. I. Oxford University Press, Clarendon.

Migahld, A.M. (J 978) Flora of Saudi A rabia. 2nd ed. Vol. I. Riyadh University, Riyadh, Saudi Arabia.

Polunln, 0 and Huxley, A. (1972) Flowers of the Mediterranean. Chatto and Windus, London.

Sabins, T.S. (1921) The Physiological anatomy of the plants of the Indian desert. Indian J. Botany. 2 (3), 61-79.

CONVOLVULUS 1 - 8;001l.te,.1 bundles.

2 - Upper Bnd )owar palisade tissues in leaves.

J - Secretory structure in leaves and stem!.

4 - Chlorenchyma in cortex of stems.

5 - Presence of trichomes.

J - Stem three nd@cs.

2 - Eglandular Irichomes ab6«n1.

J - Glandular Irichomes preSCnl.

4 - Collenchyma in leave5.

I -Stem !erele.

2 - EgJanduiar Irtchomts present J -Glandular Irichomes abscent.

4 -No collenchyma in leaves.

1 -Sttrl'wry IUUCIUfl' In pllh J -Phlot'rn has fibf('_~

I ~ Conel has chiore-n..:hym. Only 1 - Sec-re-lory struCtufe In phloem J -PhlOem hIS no fibfes

~£~

t~~

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88 A.R.Doaigey, M.J.Mady and H.A.Gawad

Table 1: Summary of common and specific anatomical cbaracters of C. arvensis, C. lanatus, and C. prostratus.

^2118.551 ^002.53^± ⁰^.05

..

²²⁰⁴^.215 ^010.77 ^± ^0.20

..

²⁴⁴⁷^.860 ⁰⁰³^.32 ^±⁰^.⁰⁸

Table 2: Relathe Intensities of 133 Ba Isotope Relative Intensity E (KeV)

Present Work McNelis & Campbell Inoue et al.

(1973) (1973)

160.63 1 .04 ± 0.16 1 .21 0.98 ± 0.07

223.10 0.76 ± 0.08 0.80 0.76 ± 0.05

276.38 11.24 ± 0.23 11.43 11.60 ± 0.50

302.71 29.61 ± 0.60 29.29 29.60 ± 1.50

356.04 100 100 100

383.85 14.66 ± 0.38 14.47 14.90 ± ⁰^.60

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..!.OO .4(

.'/---

.b.phl---~'@lIlSW

c hL ___ ::-"""'4...~/'I"""-C--~

1..---

Fig. J. Leaf of Convolvulus arvensis L.

A, midrib, upper epidermis. B, intercostal lamina, upper epidermis. C, midrib, lower epidermis. D, intercostal lamina, lower epidermis. E, intercostal lamina, transverse section. F, midrib transverse section. G, lamina, transverse section.

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90 A.R.Doaigey. M.I.Mady and H.A.Gawad

A B

•. p---

c

par

Fig. 2. Stem of C. arvensis L.

A, stem epidermis. Band C, transverse section. D, glandular trichome. E, glandular trichome, Surface view.

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F

Comparative Anatomical Studies for Three Species of Convolvulus

A

s.st_ ...

--cut

n - r - . ... _ - ' " _ u .•

-par

~~~~9.. -chi

Nv-<..N:~ ... p.m

"'~+"<~'" -I..

--~-"='=--cut

~

Fig. 3. Leaf of Convolvulus lana/us Yah!.

v.b

\

E

cut ___ ... ""--".,.

u.e--

pal --- -"''''lU.YV

91

A, intercostal lamina, upper epidermis. B, midrib, upper epidermis. C, intercostal lamina, lower epidermis. D, intercostal lamina, transverse section. E, midrib, transverse section. F, lamina, transverse section.

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92

A

B

A.R.Doaigey. M.I.Mady and H.A.Gawad

C cut- ep'"

phl---- xy--

p.phl-

Fig. 4. Stem of C. lana/us Yah!.

A, stem epidermis. Band C, transverse Section.

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A

D

Comparative Anatomical Studies for Three Species of Convolvulus

B

__ C.t

E

p .. r--- .. d.phl- - a'l---- - .. b.phl-

Fig. 5. Leaf of Convolvulus Proslralus. Forssk.

93

A, midrib, upper epidermis. B, intercostal lamina. C, upper epidermis. D, intercostal lamina, lower-epidermis. E, midrib, transverse section. F, lamina, transverse section.

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94 ^A,R, Doaigey. M,I.Mady and H,A,Gawad

B

cp-------- c.par - - - - phl.f _

cnd- phl--

.y--

p.phL m--

xy.r - - - -~-~rGm~

xy ________ _

[

P.Phl __

..!.°2,u

""N'~~

m ______ _

Fig. 6. Stem of C. Proslralus Forssk,

A, stem epidermis, Band C, transverse section,

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96 A.R. Doaigey. M.I. Mady and H.A. Gawad

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