1. Introduction
The family Crassulaceae referred to as the stone crop family consists of 34 genera and about 1,400 Species [1, 2]. They have xeromorphic features that make them to accommodate deficiency of water [3]. They are majorly perennial herbs, subshrubs, or shrubs. There was a recent classification of Crassulaceae into three subfamilies, Crassuloideae, Kalanchoideae, and Sempervivoideae [4].
The genus Kalanchoe consists of about 150 species majorly distributed in Madagascar, Africa, but they can also be found in Arabia and South-east Asia. They are generally herbs with succulent leaves. Their flowers occur in clusters [5–8]. They are mostly perennials but can also be annual plants [9, 10]. Kalanchoe species can be used as ornamentals around the world [10]. Species of Kalanchoe possess flowers that are terminal and seldom axillary flowers. Their inflorescence are corymb, paniculate, or cymose. Petals are usually four in number, stamens eight in number, and carpels four in number [10].
Bryophyllum consists of about 25 perennial succulent species that are endemic to Madagascar [11, 12]. Species of the genus Bryophyllum are garden escapes in many parts of the world, whereas few are aggressive invaders, as a result of their ease of reproduction and propagation [13, 14]. Flower morphology of two of the species have not been adequately carried out.
One of the economic importance of Kalanchoe crenata is that it is used in folk medicine as an anti-inflammatory drug. The anti-leishmanial effect has also been verified [15]. Kalanchoe lanceolata is commonly grown as an ornamental plant [16]. Bryophyllum pinnatum is also used as medicine; it has anticancer activities, antihypertensive activities among other properties [17]. Two contrasting views have been predominant in the research of the subfamily Kalanchoideae: some authors were of the opinion that the two genera should be distinguished as separate within the subfamily Kalanchoideae [18–24], whereas other authors opined that the two genera should be merged into one genus Kalanchoe [5, 11, 25].
There is a dearth of information about the flower morphology of the species studied in Nigeria, hence this study. This study aims to provide adequate description of the flower of the three Kalanchoe species in Nigeria. The morphology of the species will be described adequately.
2. Materials and methods
Collections were made in different locations in Obafemi Awolowo University, Ile ife, Osun state, Nigeria, with GPS location N07°31.252′E004°31.307′. The samples were identified through a trained herbarium curator and the use of Flora of West Tropical Africa. The species were subjected to morphological examination. Qualitative characters were described and quantitative characters were measured.
Data generated were subjected to Fisher’s least significant difference (LSD) test for mean separation as well as single linkage cluster analysis (SLCA) and principal components analysis (PCA).
3. Results
K. crenata (Andr.) Haw
Inflorescence: Cymose, terminal paniculate. They are many-flowered.
Pedicel: Green, pubescent, 0.2–0.7 cm in length.
Sepal and petal: Four in number, green, pubescent, sepals free; 0.35–0.6 cm in length and 0.1–0.2 cm in width. Petals are four in number, lobes whitish-pink in color and oblong in shape, and corolla tube light green in color. Petals is 1.6—1.9 cm in length and 0.7–1.3 cm in width.
Stamen: Filament light green with brown anther. Stamen seven in number, filament is 0.2–0.65 cm in length, and adnate with the corolla tube.
Style and stigma: Style green, 0.2–0.5 cm in length. Stigma is white.
Kalanchoe lanceolata (Forsk.) Pers
Inflorescence: Racemose, corymb.
Pedicel: Green, glabrous 0.5–1.0 cm in length.
Sepal and petal: Sepal is four in number, glabrous, pale green with cylindrical tube and deltoid lobes. Sepals joined to the petals (adnate); 2.10–2.80 cm in length and 2.10–3.00 cm in breadth. Petals are four in number, glabrous, and yellowish green with violet or red outline at the apex and margins. Petal tube cylindrical, petal lobes triangular-ovate in shape, apex acuminate, 4.10–5.00 cm in length and 2.30–2.90 cm in breadth.
Stamen: Filament light green with violet coloration; 2.60–3.40 cm in length, anther black in color, eight in number. Stamen free (Polyandrous).
Style and stigma: Style is light green, 2.50–3.40 cm long. Stigma is white.
Bryophyllum pinnatum (Lam.) Oken
Inflorescence: Cymose paniculate
Pedicel: Violet coloration, length ranges from 0.3 to 1.5 cm.
Sepal and petal: Sepal is four in number, glabrous, and pale green with violet stripes. Forms a cylindrical tube and cordate- shaped lobes. They are joined to the petal (adnate). Sepal length ranges from 2.0 cm to 3.6 cm while width ranges from 0.5 to 0.8 cm. Petals are four in number, longer than the sepal, glabrous, pale green with violet lobes. Petal tube is cylindrical with ovate-lanceolate-shaped lobes. Apex is acuminate. Petal length ranges from 2.5 to 3.8 cm and width ranges from 0.5 to 0.8 cm.
Stamen: Filament whitish-green, 1.8–3.2 cm in length. Anther is purple or violet in color when not matured and black when matured. Stamen are eight in number and joined to the wall of the corolla or petal.
Style and stigma: Style is whitish-green, 1.9–2.95 cm in length (Table 1, Figures 1–3).
Table 1
Eigenvalue and the percentage of total variation accounted for by the first two component axes of ordination of the Bryophyllum and Kalanchoe species based on the floral morphological data
| Principal components axis | Eigenvalue | Percentage of total variation | Cummulative percentage |
|---|---|---|---|
| I | 5.23375 | 74.768 | 74.768 |
| II | 1.76625 | 25.232 | 100 |
4. Discussion
Morphology has been one of the tools used in taxonomy for delimiting taxa [26]. Agbagwa et al. [27] opined that floral characters were of taxonomic value in Cucurbita species.
Their sepals and petals are generally four in number. Walters et al. [14] also reported that flowers of some genera in Crassulaceae were four in number. Koller [28] reported that inflorescence of K. crenata are many-flowered cymes, sometimes occurring as terminal corymb, and Thorat et al. [29] also reported terminal paniculate inflorescence for B. pinnatum. Cymose paniculate type was encountered in K. crenata and B. pinnatum, whereas racemose corymb type was recorded in K. lanceolata.
Sepals of the three species of genera Kalanchoe and Bryophyllum studied showed slight variation in their color. Sepal color of K. crenata is green, while that of K. lanceolata and B. pinnatum is pale green, although B. pinnatum has violet stripes with it. Notwithstanding, this character can still be used in separating the species. Inyama et al. [30] also used the sepal color to delimit three species of Chrysophyllum.
The petal color can also be employed in separation of the species studied. K. crenata has light green petals with whitish-pink lobes, K. lanceolata has yellowish green petals, and B. pinnatum has pale green petal with violet lobes. According to Inyama et al. [30], the petal color can be utilized to distinguish three Chrysophyllum species.
Anther color is another character that can be used in delimiting the species. The anther of K. crenata is brown, that of K. lanceolata is black in color, and B. pinnatum is purple when not ripe and black when ripe. This was also reported by Thiede et al. [31] who reported black and brown anther colors for some members of the family Crassulaceae.
Pubescence of sepal and sepal not joined to the petal are diagnostic characters of K. crenata. Koller [28] reported that the sepals of K. crenata were either pubescent-glandular or glabrous. B. pinnatum and K. lanceolata can be separated from K. crenata with their glabrous (smooth) sepal and their sepal joined to the petal. Smith et al. [32] described the sepal of B. pinnatum as smooth/glabrous. Smith et al. [32] recorded that the sepals of B. pinnatum were clasping the petal tube.
Sepal length of the species ranges from 0.35 to 0.6 cm in K. crenata, 2.10–2.80 cm in K. lanceolata, and 2.0–3.6 cm in B. pinnatum. Smith et al. [32] recorded that the sepal length of K. crenata was between 0.4 and 0.5 cm.
Shape of petal lobes can also be used to delineate the species: K. crenata has oblong-shaped lobes, K. lanceolata has triangular-ovate-shaped lobes, and B. pinnatum has ovate-lanceolate lobes. Walters et al. [14] also confirmed that B. pinnatum has ovate-shaped petal lobes. Koller [28] also described the shape of petal lobe as Oblong-lanceolate. Crouch et al. [33] delimited Kalanchoe winteri from Kalanchoe thyrsiflora using the shape of corolla lobes among other characters.
Petal length of the species is also useful in delimiting the species, it ranges from lowest in K. crenata and highest in K. lanceolata. Owolabi and Adedeji [34] found out that the petal length among other characters were more useful to delineate generas and tribes in the subfamily Papilionoideae.
The species can be separated with whether the stamen is joined to the petal or not. K. crenata and B. pinnatum’s stamen are joined to the petal, whereas the stamen of K. lanceolata is not joined to the stamen. Walters et al. [14] observed that the stamen of B. pinnatum was inserted below the middle of their petals. Smith et al. [32] reported that the stamen of K. crenata were inserted just above the middle of corolla tube.
Pedicel length varies slightly with B. pinnatum being the highest and K. crenata being the lowest. Owolabi and Adedeji [34] delineated the species within the genus Desmodium using their pedicel length and other characters.
The morphology of the floral parts of three species studied revealed two main cluster, K. lanceolata and K. crenata clustered together in the first main cluster at 65% similarity index, whereas B. pinnatum was separated in the second main cluster (Figure 1).
From the principal components analysis of the floral morphological characters of the Bryophyllum and Kalanchoe species studied, the first three components of the PCA accounted for 100% of the variation among the species studied. From the PCA loadings, the components accountable for the variations observed among the species are the petal length, the filament length, and the style length (Figure 2).
Figure 2
Principal components analysis showing the relationship of the Bryophyllum and Kalanchoe species based on floral morphological characters for components 1 and 2.
Figure 3
Flower morphology of the three Kalanchoe species studied (a) Inflorescence of K. crenata (b) Inflorescence of K. lanceolate (c) Flower showing style, stigma, anther, and pollens of K. lanceolate (d) Sepal of K.l anceolata (e) Flower showing petal and pollens of K. lamceolata (f) Inflorescence of B. pinnatum (g) Flower of B. pinnatum.
5. Conclusion
Attributes that can be used to delimit the taxa such as petal color, sepal color and anther color, pubescence or glabrousness of sepal, shape of petal lobes, and length of petal, sepal, and filament were documented. Unifying attributes such as petals and sepals four in number were also recorded.
Identification key for the three species studied
Sepal 4 in number and Petal 4 in number: Kalanchoe crenata, Kalanchoe lanceolata, and Bryophyllum pinnatum
Pedicel color green: Kalanchoe crenata and Kalanchoe lanceolata
Sepal glabrous, adnate, anther color black and stamen 8 in number: Kalanchoe lanceolata and Bryophyllum pinnatum
Petal color light green with whitish-pink lobes, sepal color green, anther color brown, and inflorescence cymose terminal paniculate: Kalanchoe crenata
Petal color yellowish green with violet outline, sepal color pale green, and inflorescence racemose corymb: Kalanchoe lanceolata
Petal color pale green with violet lobes, sepal color pale green with violet stripes, and inflorescence cymose paniculate: Bryophyllum pinnatum
