Journal of Plant Sciences
Volume 3, Issue 3, June 2015, Pages: 111-116

A Study of Foliage Morphological Descriptions Accommodating Continuity in Previous Delimitation of Types in Tropical Plants

Fawibe Oluwasegun Olamide*, Ogunyale Omolara Grace, Oyelakin Abiodun Sunday, Ayodele Muyiwa Segun

Department of Pure and Applied Botany, Federal University of Agriculture Abeokuta, Ogun State, Nigeria

Email address:

(O. O. Fawibe)

To cite this article:

Fawibe Oluwasegun Olamide, Ogunyale Omolara Grace, Oyelakin Abiodun Sunday, Ayodele Muyiwa Segun. A Study of Foliage Morphological Descriptions Accommodating Continuity in Previous Delimitation of Types in Tropical Plants. Journal of Plant Sciences. Vol. 3, No. 3, 2015, pp. 111-116. doi: 10.11648/j.jps.20150303.11


Abstract: The morphological description of some selected tropical plants in Ogun State, Nigeria was investigated. This is with a view to bridge existing more or less compartmentalized foliar descriptions which are discrete and lack the observed continuum of shape types in nature. Plants from which leaves were collected and observed for the different traits were randomly collected from some Local Government Areas of the State. The qualitative macromorphological characters observed include, leaf type, leaf shape, leaf apex, leaf base and leaf margin with varying percentage occurrence. Of the 74 distinct foliage types examined 62(84%) matched the existing foliage descriptions in literature while 12(16%) had undefined shape descriptions. It was observed that simple (79%), ovate and lanceolate (18%), entire (58%), acute (26%), acute (44%) had the highest frequency for the leaf type, leaf shape, leaf margin, leaf apex and leaf bases respectively, while the lowest frequency was recorded to be compound (21%), linear, oblanceolate, acicular, orbicular, sagitate, falcate, peltate, hastate, lobed (1.6%), spinose, denticulate, crenate, parted (1.6%), mucronulate and cirrhose (1.6%), auriculate and hastate (1.6%) in the leaf type, leaf shape, leaf margin, leaf apex and leaf bases respectively. Other shapes hitherto undefined include: lanceospatulate, zygomorphic-trilobe, ensiformis, lobed-pentate, lobed-starlate and ellipto-dentoid. The study revealed that there is a continuum in plant foliage macromorphological description rather than independent occurrence of plant foliage characters found in literature.

Keywords: Foliage, Qualitative, Morphology, Delimitation


1. Introduction

There are various descriptive terminologies in literature for plant foliage. These all present the different aspects of plant leaves in more or less compartmentalized groups which may not actually leave room for the usually observed continuity in variation of forms in nature. The usefulness of these existing descriptions cannot be overemphasized judged by their application by Taxonomists and Biosystematists. 

Plant leaves are normally regarded as possessing useful characteristics for species identification [1,7,8,4] However, Gwo and Wei (2013) in expressing the premise for their own study, highlighted the fact that plant identification demands extensive knowledge and such complex terminologies which even professional Botanists would require significant time in the field for mastery of the subject. One of the reasons for such challenges may not be far removed from non-accommodation of some forms intermediate in current descriptions.

The subject of leaf traits has been reported as having a relationship with different ecological and physiological factors [16,5,3,13,17]. The functional significance of shape variation among leaves has been the subject of debate for many years; and there are a range of different approaches to describing leaf shape [7]. The diversity of shape suggests that there is no one ecological strategy that is dependent exclusively on leaf shape. Even within a single genus, leaf shape variation can be tremendous [8]. 

Leaves exhibit a remarkable diversity of shapes that range from developmental sequences within a shoot and within crown response to immediate environment; to variation among species within and between communities and among orders or families [8].  Many plant traits are sensitive to climate [16,3].  Compared with warmer sites, colder sites contained species whose leaves generally had more teeth, a larger tooth area and a higher perimeter-to-area ratio [12]. Thus the need for this current study arises, with a view to presenting if any, those forms and shapes not considered in the descriptions currently available.

2. Materials and Methods

Plants from which leaves were collected and observed for the different traits under study were obtained from surrounding forests of Abeokuta Metropolis, Nigeria.  These are tropical plants in typical rain forest locations which include: Osiele, Camp, Obantoko, FUNAAB community in Odeda Local Government Area (7˚11̍ 51˝N - 32˚6̍12˝ E); Olomore, in Abeokuta North Local Government Area (7˚9̍39˝N - 3˚20̍54˝E).

Leaf specimens severed from the plants by means of secatures, were collected in labelled polythene bags containing the plant locations, habitat growth form and position on the plants. The specimens were later prepared for preservation as described by [9]. Preserved specimens were mounted on cardboard and their pictures recorded by means of a NIKON Coolpix P90 digital model camera.  Voucher specimens were deposited at the Herbarium. Qualitative characters such as leaf types, shapes, margin, base and apex were observed and scored as they occurred and recorded.  The leaf characters were identified in line with existing records in various Flora and some text books.

Descriptive statistics such as frequency distribution, bar chart were used in the analysis of the data.

3. Results

Majority of the leaves examined (80%) from the different plants under study were of the Simple leaf Category. The leaf shapes more pronounced in occurrence in this study were Ovate and Lanceolate (18%); while the least occurring shapes were Linear, Oblanceolate, Acicular, Orbicular, Sagitate, Falcate, Peltate, Hastate and Lobed (1.6%) respectively (Figure 2). The leaf margin type with the highest frequency of occurrence was Entire (58%), followed by the Serrate margin type (28%) Other margin types were not too conspicuous (Figure 3). The common leaf Apex forms and their percentage of occurrence include and in descending order: Acute (26%), Apiculate (22%), and Acuminate (19%) Figure 4. The most pronounced leaf base type was Acute (44%). Other fairly noticeable types ranging between 16 - 18% were Rounded and Attenuate (Figure 5). Table 1 gives a holistic idea of the relative combinations of these qualitative attributes among the leaves of the different plants examined.

Figure 1. Frequency of the leaf types among studied specimens

Figure 2. Frequency of leaf shape among studied specimens

Figure 3. Frequency of the leaf margin among studied specimens

Figure 4. Frequency of the leaf apex among studied specimens

Figure 5. Frequency of the leaf base among studied specimens

Of the 74 distinct foliage types collected and examined, 62 (84%) matched the existing foliage descriptions in literature and available Flora, while 12 (16%) had undefined shape description. These had leaf qualitative traits observed among the plants examined (Figure 6) that would not readily fit into any of the existing described delimitation of types. These were separated for further comparative examination with a view to assigning an appropriate character nomenclature. Their leaf shape features and how they combine other morphological details were duly presented in Table 1. Suggestive descriptive names are as in Table 2; consisting of 9 leaf shapes and one each of leaf Apex and Margin and two of leaf Base. A glossary of the suggested descriptive terminologies are provided in Table 3.

Figure 6. Pictures of leaves with undefined features and their suggested nomenclature (a) Lanceospatulate (b) Forkate (c) Starlate (d) Lobed-starlate (e) Zygomorphic trilobe (f) Ensiformate (g) Lobed -pentate (h) Octopulate (i) Ellipto-dentoid (j) Serro-dentate (k) Pinoid (l) Simpo-compound

Table 1. Qualitative morphological characters of different leaves examined

S/N LEAF TYPE LEAF SHAPE LEAF APEX LEAF BASE LEAF MARGIN
1. Simple Linear Acuminate Acute Entire
2. Simple Obovate Acute Acute Sinuate
3. Simple Deltoid Apiculate Acute Serrate
4. Simple Elliptical Aristate Acute Serrate
5. Simple Deltoid Acute Oblique Serrate
6. Simple Ovate Apiculate Auriculate Serrate
7. Compound Oblong Obtuse Rounded Entire
8. Compound Ovate Acute Rounded Entire
9. Simple Oblanceolate Acute Acute Entire
10. Simple Lanceolate Apiculate Acute Entire
11. Simple Lanceolate Apiculate Acute Serrate
12 Simple Oblong Retuse Acute Crenate
13 Simple Lobed Apiculate Acute Serrate
14 Simple Ovate Apiculate Rounded Entire
15 Simple Elliptical Aristate Rounded Serrate
16 Simple Ovate Acuminate Attenuate Serrate
17 Simple Obovate Acute Attenuate Entire
18 Compound Lanceolate Acuminate Oblique Serrate
19 Simple Acicular Acuminate Attenuate Entire
20 Simple Cordate Apiculate Cordate Entire
21 Simple Elliptical Mucronulate Rounded Entire
22 Simple Cordate Acute Cordate Serrate
23 Simple Orbicular Acute Cordate Serrate
24 Simple Obovate Retuse Acute Entire
25 Simple Ovate Aristulate Oblique Spinose
26 Simple Rhomboidal Aristulate Acute Serrate
27 Compound Ovate Acuminate Acute Entire
28 Compound Ovate Acute Acute Serrate
29 Compound Lanceolate Apiculate Acute Entire
30 Simple Obovate Cirrhose Attenuate Denticulate
31 Compound Lanceolate Aristate Acute Entire
32 Simple Elliptic Acute Attenuate Entire
33 Simple Cordate Apiculate Cordate Serrate
34 Simple Cuneate Retuse Acute Entire
35 Simple Obovate Obtuse Acute Entire
36 Simple Elliptical Apiculate Attenuate Sinuate
37 Simple Rhomboidal Acute Acute Serrate
38 Simple Obovate Obtuse Acute Entire
39 Simple Ovate Apiculate Attenuate Serrulate
40 Compound Lanceolate Acuminate Acute Entire
41 Simple Elliptical Retuse Acute Entire
42 Compound Rhomboidal Acuminate Acute Parted
43 Simple Ovate Acute Cordate Sinuate
44 Simple Lanceolate Acuminate Attenuate Entire
45 Simple Ovate Acuminate Acute Entire
46 Simple Lanceolate Acuminate Rounded Entire
47 Simple Ovate Aristate Rounded Serrulate
48 Simple Deltoid Acute Rounded Entire
49 Simple Deltoid Acute Rounded Serrulate
50 Simple Sagitate Apiculate Sagitate Entire
51 Simple Lanceolate Aristate Acute Entire
52 Compound Elliptical Retuse Rounded Entire
53 Simple Obovate Obtuse Attenuate Entire
54 Compound Falcate Acuminate Attenuate Entire
55 Simple Cuneate Obtuse Attenuate Entire
56 Simple Obovate Apiculate Acute Entire
57 Simple Lanceolate Aristulate Rounded Entire
58 Compound Oblong Obtuse Rounded Entire
59 Simple Elliptical Acute Acute Entire
60 Compound Lanceolate Acuminate Acute Sinuate
61 Simple Peltate Acute Sagitate Entire
62 Simple Hastate Acute Hastate Entire

Table 2. Morphological features of undefined leaf characters (in bold print)

FIGURE 6 LEAF SHAPE LEAF APEX LEAF BASE LEAF MARGIN
a Lanceospathulate Acute Rounded Entire
b Forkate Acuminate Attenuate Serrulate
c Starlate Acuminate Auriculate Serrulate
d Lobed-starlate Acuminate Sagitate Lobate
e Zygomorphictrilobe Acute Acute Entire
f Ensiformate Acute Acute Entire
g Lobed-pentate Obtuse Auriculate Lobate
h Octopulate Acute Auriculate Sinuate
i Ellipto-dentoid Obtuse Acute Double –dentate
j Ovate Acute Acute Serrodentate
k Filiform Pinoid Pinoid Entire
l Ovate Acute Simpo-compound Sinuate

Table 3. Glossary of upgraded foliar descriptions

Terminology Description
Lanceospatulate A lance-shaped leaf with a broad apex which tappers at the middle to give a broad base
Forkate Starlate Fork - shaped leaf Star - shaped leaf
Lobed-starlate A lobed star - shaped leaf
Zygomorphic-trilobe A simple leaf with two sides lobed at equal angle from the same axis.
Ensiformate Lobed-pentate Sword- shaped leaf A five - lobed shaped leaf.
Octopulate Ellipto-dentoid Octopus- shaped leaf An Elliptic-shaped leaf with dentate margin
Serrodentate Leaf with serrate margin towards the apex and dentate margin towards the base
Pinoid apex and base A sharp pointed apex and base
Simpo-compound A leaf that looks simple towards the apex but splits towards the base into leaflets

4. Discussion

Plant leaves manifest a remarkable diversity of shapes, margins, apices and bases that range from developmental sequences within and between communities.

Morphologically, the leaves in the area studied were predominantly simple with acute apex, entire margin and acute base. These results were similar to those of species from other tropical rainforest vegetation [6,2]. This similarity might have resulted from comparable species composition and/or from convergent development as a response to similar environmental condition [10].

The less occurrence of compound leaves compared to simple leaves in this region could be attributed to the ecological factors of this region. This was supported by [14] who reported that compound leaves seem to be more common in warmer and arid or semi-arid environments and in light demanding species. Their shape, arrangement and construction are thought to offer advantages in capturing light while reducing water loss and maintaining lower leaf lamina temperatures.

Ovate leaves with acute or acuminate apex and entire margins prominent in these areas can be associated with the high pluviosity of the area [6]. It has been suggested that this leaf morphology worked as drainage triggerers [11] which probably retards the growth of epiphylls and reduces loss of soluble nutrients by leaching [15].

Shape, margin, apex and base variation among leaves have been the subject of debate for many years. The undefined leaf qualitative traits among the plants observed showed that there is a continuum in plant foliage morphology rather than independent occurrence of foliar description has appeared in text. Proposed leaf margin such as Serro-dentate, may fill the gap between the serrate and dentate margin while the Lanceospathulate may bridge the gap between the Lanceolate and Spathulate leaf shape. Understudied foliage also showed some "Shapes" attributes which better described them than generalized acronym. Proposed leaf shape such as Zygomorphic-trilobed, Ensiformate and Starlate showed better description than "lobed" as appeared in literature.

The study revealed that there is a continuum in plant foliage macromorphological description rather than independent occurrence of plant foliage characters found in literature.


References

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