Curvature Analysis in Seed Surface of SEM Images of Silene Species from Türkiye

: Recently, based on light microscopy images, the tubercle structure on the seed surface of 100 Silene species was quantitatively described, including tubercle width, height, and curvature associated with general morphometric data. Curvature measures the rate of change of the tangent vector in a curve and can be calculated by the following methods described for Arabidopsis roots. Here, we apply curvature measurements to the SEM images of 40 Silene species from Türkiye, demonstrating that a quantitative analysis of tubercles can be made based on SEM images with similar results to optical photographs. The association of morphometric tubercle data allows for classification into six groups, five of them corresponding to described shapes: rugose (two groups), echinate, mammillate, and papillose, and a sixth group of tubercles plane on top. The curvature values vary between 20 and 200 mm − 1 and differ among the morphological tubercle types described. The correlation of curvature values with other general measurements and morphological seed characteristics is investigated. Tubercle quantification not only is a useful tool for Silene taxonomy, but also provides the basis for the analysis of the genetic control and developmental effects on tubercle structure and shape in the seed surface.


Introduction
The fruits and seeds of many plant species present distinct surface protrusions, often associated with various types of dispersion [1].Thus, winged fruits and seeds occur in species of 93 families at least [2][3][4], being frequent in climbers such as the Aristolochiaceae [5] and Cucurbitaceae [6], and absent or not described in the Arecaceae.Seed surface formations may also contribute to zoochory or hydrochory, as the endocarp fibers of Chamaedorea cataractarum Mart.[7] and other outgrowths may play a role as mechanisms facilitating the establishment and support of seeds in rocks and cliffs [8][9][10].
In the Caryophyllaceae and other families of the order Caryophyllales, winged seeds are rare [11].However, the name Dipterospermae (Rohrb.)was applied to a section in the Silene subgen.Silene, now ascribed to sect.Silene [12].The lateral view of seeds in this section resembles a butterfly, and the two lateral projections are called wings, but there is no evidence for the role of these structures in wind transport.Nevertheless, the diversity of tubercle size and shape in the Caryophyllaceae has attracted the attention of botanists for generations, and even the genera were named considering seed morphological peculiarities, such as Heliosperma (Rchb.)Rchb., due to long tubercles that expand from the central part of the seed, giving it a radiated shape akin to the rays of the sun (Helios).Tubercle structure has been proposed as a key character in the genera of the order Caryophyllales, for example, Portulaca L. (Portulacaceae) [13,14], and in many genera of the Caryophyllaceae, such as Arenaria Ruppius ex L. [15][16][17][18], Cerastium Tourn.ex L. [15,18,19], Minuartia Loefl.[18,20], Moehringia L. [21,22], Sagina L. [23,24], and Stellaria L. [15,18,19,[25][26][27][28] in the Alsineae; Acanthophyllum C.A.Mey [29,30], Dianthus L. [23], and Gypsophilla L. [23,31,32] in the Caryophylleae; Paronychia Mill.(Paronichieae) [33,34] and Silene L.  (Sileneae).However, evidence for a physiological and/or ecological function of seed surface tubercles is very scarce in this order.After observation in many species, mainly with SEM (Scanning Electron Microscopy), and classification into morphological types, the ecological functions of the tubercles remain largely unexplained except for a general role of support and attachment of the seeds to the substrate in rocks and cliffs against dragging by water and wind [8][9][10].
Recent work based on the quantification of geometric measurements in light microscopy images proposed a broad classification of the tubercles in the genus Silene in four types: smooth, rugose, echinate, and papillose [62,63].Smooth seeds are defined by the absence of visible protuberances and were described before in Arenaria L. [15][16][17], Minuartia L. [20], Moehringia L. [22], and Silene [37,38,49].Some species belonging to the S. subgen.Silene sect.Silene presented smooth seeds.These seeds are characterized by high circularity and solidity values in their lateral views, while in their dorsal views, higher circularity values are shared by echinate and rugose seeds [62].In contrast to smooth seeds, the papillose seed group in Silene is characterized by the largest protuberances, resulting in the lowest values of circularity and solidity in both lateral and dorsal views.It includes the species S. holzmani Heldr.ex Boiss.(sect.Behenantha), S. laciniata Cav.(sect.Physolychnis), S. magellanica (Desr.)Bocquet (sect.Physolychnis), S. perlmanii W.L.Wagner, D.R.Herbst & Sohmer (sect.Sclerophyllae) [63].Rugose and echinate seeds are distinguished by their tubercle types, being more rounded in the former type and more triangular or acute in the second.Geometrically, these two types of tubercles are well differentiated by analysis of their curvature values, higher in echinate than in rugose tubercles [64].Concerning the taxonomy of the genus, although there is not a clear-cut difference between subgenera, nevertheless, the smooth and rugose types are more frequent in the S. subgen.Silene.The echinate type of higher curvature values occurs more often in the S. subgen.Behenantha [64].
The curvature of a curve is the rate at which the unit tangent vector changes with respect to arc length [65][66][67].The methods here applied for curvature measurements are based on those developed for the analysis of the root apex in Arabidopsis Heynh.(Brassicaceae) [65,66].This methodology was also applied to the seeds of wheat, grape, Cucurbitaceae, and some species of Silene [64,[67][68][69][70][71].
The first objective of this work was to implement a set of methods for the analysis of the curvature on the surface of Silene seeds from SEM images and to demonstrate that the methodology can be applied both to SEM images and to optical microscopy photographs, providing equivalent and consistent data.The second objective was to obtain an accurate measurement of the curvature of individual seed tubercles to analyze their distribution and types in the Silene species from the Turkish SEM image collection.

Seed Images
This work is based on the SEM images of the Turkish collection of images corresponding to 122 Silene species maintained by K. Yildiz.The collection contains seed images taken at 100× that were used in this work, making this approach more comparable to our work with light microscopy.

Curvature Measurement
The curvature was measured in pairs of tubercles to obtain the values in two adjacent peaks and in the curve between them.The coordinates of points along the tubercles were automatically derived from their images with Image J and processed with the Mathematica program designed first to give their Bézier curve and second to calculate the corresponding curvature values along the curve, as described in Refs.[64][65][66][67].Tubercle images were oriented with their peaks upwards and opened with Image J.After size adjustment with the ruler of each image, selected regions were thresholded, and the corresponding (x,y) coordinates were copied and processed to Mathematica.Bézier curves and the corresponding curvature values resulted from published protocols [64][65][66][67] (see Supplementary Data).Curvature is given in mm −1 ; thus, a curvature of 20 belongs to a circumference of 50 microns while a curvature of 2 is associated with a circumference of 500 microns (0.5 mm).For most species analyzed, four pairs of tubercles were measured.The images and corresponding Mathematica files are available as indicated in the Supplementary Materials section.

Statistical Analysis
For each group of seeds, the mean values and coefficients of variation were obtained for general morphological measurements and tubercle measurements (curvature, width, height).For morphological characteristics and curvature analysis, the data did not adjust to normal distributions, and the Kruskal-Wallis test was applied, followed by stepwise stepdown comparisons by the ad hoc procedure developed by Campbell and Skillings [73]; p values below 0.05 were considered significant.The coefficient of variation was calculated as CVtrait = standard deviationtrait/meantrait × 100 [74].Statistical analyses were conducted with IBM SPSS statistics v29 (SPSS 2022).
The Euclidean distance and Ward algorithm for clustering were used to calculate the dendrogram.The matrix used for the analysis contained the data for general morphological measurements (Appendix A, Tables A1-A6) and tubercle measurements of curvature values, as well as tubercle width (W), height (H), and slope.
Sections 3.1-3.6contain the description and examples of tubercle measurements in each of these six groups; Section 3.7 contains the comparison between groups.
A summary of the general morphological measurements is presented in
A summary of the general morphological measurements is presented in Table A2 (Appendix A) and the tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 3. Figure 3
A summary of the general morphological measurements is presented in Table A2 (Appendix A) and the tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 3. Figures 3 and 4, correspond, respectively, to S. oreophila and S. phrygia contain examples of tubercles of this group.
A summary of the general morphological measurements is presented in Table A3 (Appendix A) and the tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 4. Figures 5 and 6, corresponding, respectively, to S. italica and S. tenuiflora, contain examples of tubercles of this group.
The seed tubercles in this group are rounded and umbonated (with mammillae).The curvature values, more variable than the other groups due to two types of tubercles (umbonated or not), are comprised between 25.6 and 183.7 mm −1 .Inter-tubercle curvature is comprised between 25.0 and 169.3.The tubercles of these seeds are mainly rounded and have mean curvature values comprised between 18.7 and 72.3 mm −1 .Inter-tubercle curvature is comprised between 26.3 and 133.7.
A summary of the general morphological measurements is presented in Table A3 (Appendix A) and the tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 4. Figures 5 and 6, corresponding, respectively, to S. italica and S. tenuiflora, contain examples of tubercles of this group.
A summary of the general morphological measurements is presented in Table A4 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 5. Figure 7, Figure 8, and Figure 9, corresponding, respectively,
A summary of the general morphological measurements is presented in Table A4 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 5. Figure 7, Figure 8, and Figure 9, corresponding, respectively, to S. anatolica, S. cserei, and S. rhynchocarpa, contain examples of tubercles of this group.
The curvature graphs of tubercles in this group are characteristic, with at least three The seed tubercles in this group are rounded and umbonated (with mammillae).The curvature values, more variable than the other groups due to two types of tubercles (umbonated or not), are comprised between 25.6 and 183.7 mm −1 .Inter-tubercle curvature is comprised between 25.0 and 169.3.
A summary of the general morphological measurements is presented in Table A4 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 5. Figures 7-9, corresponding, respectively, to S. anatolica, S. cserei, and S. rhynchocarpa, contain examples of tubercles of this group.
A summary of the general morphological measurements and curvature analysis is shown in Table A5 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 6. Figure 10 and Figure 11, corresponding, respectively, to S. isaurica and S. conica, contain examples of tubercles of this group.
Tubercles in this group have mean curvature values comprised between 61.4 and 109.4 mm -1 .Inter-tubercle curvature is comprised between 31.9 and 187.7.The curvature graphs of tubercles in this group are characteristic, with at least three peaks per tubercle, two peaks at the extremes of high curvature values, and at least one peak between them of a lower curvature.Tubercles have mean curvature values comprised between 29.7 and 56.4 mm −1 .Inter-tubercle curvature is comprised between 56.2 and 261.4.
A summary of the general morphological measurements and curvature analysis is shown in Table A5 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 6.Figures 10 and 11, corresponding, respectively, to S. isaurica and S. conica, contain examples of tubercles of this group.Tubercles in this group have mean curvature values comprised between 61.4 and 109.4 mm −1 .Inter-tubercle curvature is comprised between 31.9 and 187.7.

Seeds with Papillose Tubercles
This group includes seeds of three species, two of S. subgen.Silene: S. echinospermoides (Rigidulae), and S. leptoclada (Siphonomoprpha); and one to S. subgen.Behenantha: S. lydia (Conoimorpha).A summary of the general morphological measurements is shown in Table A6 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 7. Figure 12, corresponding to S. echinospermoides, contains examples of tubercles of this group.

Seeds with Papillose Tubercles
This group includes seeds of three species, two of S. subgen.Silene: S. echinospermoides (Rigidulae), and S. leptoclada (Siphonomoprpha); and one to S. subgen.Behenantha: S. lydia (Conoimorpha).A summary of the general morphological measurements is shown in Table A6 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 7. Figure 12, corresponding to S. echinospermoides, contains examples of tubercles of this group.

Seeds with Papillose Tubercles
This group includes seeds of three species, two of S. subgen.Silene: S. echinospermoides (Rigidulae), and S. leptoclada (Siphonomoprpha); and one to S. subgen.Behenantha: S. lydia (Conoimorpha).A summary of the general morphological measurements is shown in Table A6 (Appendix A).Tubercle measurements (curvature analysis, tubercle height, width, and slope) are shown in Table 7. Figure 12, corresponding to S. echinospermoides, contains examples of tubercles of this group.

Comparison between Seed Groups Based on Tubercle Type
There were differences between groups for the morphological data (Table 8), as well as for tubercle measurements of width, height, and curvature (Table 9).In all distancebased measurements (A, P, L, W), a group of higher values corresponded to the first group of small tubercle seeds, and lower values were observed in the remaining groups, except plane tubercle seeds in area and width, plane and papillose tubercle seeds in perimeter, and plane and broad tubercle seeds for length.Circularity was higher in small and lower in papillose seeds.The aspect ratio was higher in broad and lower in mammillate seeds, and the inverse result was observed for roundness.Solidity was higher in the seeds of small tubercles and lower in the seeds with echinate and papillose tubercles.
Table 8.Morphological measurements for seeds.Mean values (coefficient of variation) for Area (A), Perimeter (P), Length (L), Width (W), Circularity (C), Aspect Ratio (AR), Roundness (R), and Solidity (S) in the seed types considered according to their tubercle shape.Different superscript letters in the same column indicate significant differences from Campbell and Skillings analysis (p < 0.05).

Comparison between Seed Groups Based on Tubercle Type
There were differences between groups for the morphological data (Table 8), as well as for tubercle measurements of width, height, and curvature (Table 9).In all distance-based measurements (A, P, L, W), a group of higher values corresponded to the first group of small tubercle seeds, and lower values were observed in the remaining groups, except plane tubercle seeds in area and width, plane and papillose tubercle seeds in perimeter, and plane and broad tubercle seeds for length.Circularity was higher in small and lower in papillose seeds.The aspect ratio was higher in broad and lower in mammillate seeds, and the inverse result was observed for roundness.Solidity was higher in the seeds of small tubercles and lower in the seeds with echinate and papillose tubercles.Differences between groups were also observed in curvature values as well as in tubercle width, tubercle height, and slope (Table 9).
The dendrogram in Figure 13 shows the relationship between the groups formed on the basis of tubercle morphology.Most species of S. subgen.Silene have lower curvature values and are grouped in the upper part of the diagram.
Differences between groups were also observed in curvature values as w bercle width, tubercle height, and slope (Table 9).The dendrogram in Figure 13 shows the relationship between the group the basis of tubercle morphology.Most species of S. subgen.Silene have low values and are grouped in the upper part of the diagram.

Discussion
Silene L., with about 850 species, is the largest genus of Caryophyllaceae [12].In addition to a model for infrageneric diversity, S. latifolia, S. dioica, and other species [75] have been proposed as models for the study of sex determination.Like humans, these species have heteromorphic chromosomes, with a rapidly evolving non-recombining Y region rich in repetitive DNA that provides a unique system for the study of the origin and modification of sex chromosomes [76].Silene species also present variations in seed shape that can be quantified by different means.The overall seed shape can be compared with geometric objects, and in many species, the lateral seed views show striking similarities with the cardioid and derived models [68].Tubercle size, shape, and distribution can also be studied using geometrical and statistical methods [68,77].
Most descriptions of the seed surface in Silene are based on SEM images, and the terms to describe the shape of tubercles include conical [51], convex [55], cylindrical [51], echinate [55], granulate [45], mammillate (umbonated) [51,55], papillose [48], rounded [55], and winkled [36].In general, although there may be different representations of these types in the different sections, there is no ascription of these particular types to any sections or subgenus.Based on seed silhouettes derived from light microscopy images, we classified the tuberculated seeds into three types: rugose, echinate, and papillose.Curvature analysis revealed higher values in the echinate than in the rugose-type tubercles [64].Following our previous terminology, in this work, the seeds were classified into six groups.Groups 1 and 2 consisted of rugose seeds, which were differentiated by seed size and tubercle width.Groups 3 and 4 were made up of mammillate seeds and seeds with flat tubercles on top.Groups 5 and 6 contained echinate and papillose seeds, respectively.In accordance with previous results [62,63], these groups are supported based on morphological measurements.Thus, papillose seeds had lower circularity than the two groups of rugose seeds, and both papillose and echinate seeds had lower solidity values than the rugose seeds.There is also a difference between the two rugose groups based on area, perimeter, length, and width.According to these measurements, mammillate seeds are closer to seeds with broad rugose tubercles than to seeds with small rugose tubercles.However, the mammillate group differs from the two rugose groups in tubercle dimensions, whereas it differs from the group of small rugose tubercles in tubercle curvature.Differences between groups are noticeable in the maximum curvature, with lower values in the two groups of rugose seeds, and higher in the papillose seed group.
Unlike groups 1, 2, and 3, groups 4, 5, and 6 are more diverse.The tubercles of Group 4 have a very characteristic shape-plane at the top.Although this type is clearly distinguishable to the naked eye, it also has noteworthy geometrical features.The tubercles had a profile with two lateral maxima and a central point of lesser curvature, and the curve between tubercles had higher curvature values than in any of the other types.In addition to the examples reported here, some populations of S. behen also have such tubercles [57].In the seeds of Group 4 studied here (see Table 5), higher curvature values and higher tubercles corresponded to S. cserei, and smaller ones to S. rhynchocarpa.The low-plane tubercles of S. rhynchocarpa seed resemble those of Groups 1 and 2.
The work reported here confirms a certain association between tubercle type and taxonomic sections.Groups 1 to 3 contain almost exclusively species of S. subgen Silene.Species in Groups 1 and 2 (rugose, or rounded tubercles) belong to the Silene subgen.Silene.The difference between these two groups lies in the size of the seeds and the width of the tubercles.While the seeds of Group 1 are large and have smaller tubercles, the seeds of Group 2 are smaller and have tubercles broader at the base.

Figure 1 .
Figure 1.Left: a seed of S. caryophylloides with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 1 .
Figure 1.Left: a seed of S. caryophylloides with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.The tubercles of the seeds in this group are rounded and have mean curvature values comprised between 24 and 40.8 mm −1 .Inter-tubercle curvature is comprised between 30.1 and 95.6.

Figure 1 .
Figure 1.Left: a seed of S. caryophylloides with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 2 .
Figure 2. Left: a seed of S. chlorifolia with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.
and Figure 4, correspond, respectively, to S. oreophila and S. phrygia contain examples of tubercles of this group.

Figure 2 .
Figure 2. Left: a seed of S. chlorifolia with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 3 .
Figure 3. Left: a seed of S. oreophila with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 4 .
Figure 4. Left: a seed of S. phrygia with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 5 .
Figure 5. Left: a seed of S. italica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 6 .
Figure 6.Left: a seed of S. tenuiflora with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 5 . 10 Figure 5 .
Figure 5. Left: a seed of S. italica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 6 .
Figure 6.Left: a seed of S. tenuiflora with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 6 .
Figure 6.Left: a seed of S. tenuiflora with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 7 .
Figure 7. Left: a seed of S. anatolica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 8 .
Figure 8. Left: a seed of S. cserei with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 7 .
Figure 7. Left: a seed of S. anatolica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 7 .
Figure 7. Left: a seed of S. anatolica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 8 .
Figure 8. Left: a seed of S. cserei with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 8 .
Figure 8. Left: a seed of S. cserei with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 9 .
Figure 9. Left: a seed of S. rhynchocarpa with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 9 .
Figure 9. Left: a seed of S. rhynchocarpa with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 10 .
Figure 10.Left: a seed of S. isaurica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 11 .
Figure 11.Left: a seed of S. conica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to two pairs and two individual tubercles.

Figure 10 .Figure 10 .
Figure 10.Left: a seed of S. isaurica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to the four pairs of tubercles.

Figure 11 .
Figure 11.Left: a seed of S. conica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to two pairs and two individual tubercles.

Figure 11 .
Figure 11.Left: a seed of S. conica with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to two pairs and two individual tubercles.

Figure 12 .
Figure 12.Left: a seed of S. echinospermoides with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to two pairs and one individual tubercle.

Figure 12 .
Figure 12.Left: a seed of S. echinospermoides with eight tubercles numbered (below, scale).Right: tubercle images, Bézier curves, and curvature plots corresponding to two pairs and one individual tubercle.

Figure 13 .
Figure 13.Dendrogram based on hierarchical clustering with the values of tubercle m indicated in Tables 2 to 7 and seed morphological measurements (Tables A1-A6).

Figure 13 .
Figure 13.Dendrogram based on hierarchical clustering with the values of tubercle measurements indicated in Tables 2-7 and seed morphological measurements (TablesA1-A6).

Table 1 .
[72].Silene anatolica Melzheimer & A. Baytop are very similar to S. cserei.In the Flora of the Caucasus[72], S. anatolica is given as the synonym of S. cserei.However, S. cserei and S. anatolica are different species in terms of characteristics such as base and stem leaf sizes, calyx veining, and anthophore length.Therefore, the species S. anatolica is not a synonym for the species S. cserei, and both are separate species. *:

Table A1 (
Appendix A) and tubercle measurements (curvature analysis, tubercle height, width and slope) are shown in Table 2. Figures 1 and 2 correspond, respectively, to S. caryophylloides and S. chlorifolia and contain examples of tubercles of this group.

Table 2 .
Tubercle measurements in seeds of Group 1. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 3 .
Tubercle measurements in seeds of Group 2. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 4 .
Tubercle measurements in seeds of Group 3. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 5 .
Tubercle measurements in seeds of Group 4. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 5 .
Tubercle measurements in seeds of Group 4. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 5 .
Tubercle measurements in seeds of Group 4. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 6 .
Tubercle measurements in seeds of Group 5. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 6 .
Tubercle measurements in seeds of Group 5. Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.N indicates the number of tubercles measured in each species.

Table 7 .
Tubercle measurements in seeds of Group 6. N is the number of tubercles analyzed per species.Mean values (coefficient of variation) for each species are given for the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width (W), tubercle height (H), and slope.

Table 8 .
Morphological measurements for seeds.Mean values (coefficient of variation) for Area (A), Perimeter (P), Length (L), Width (W), Circularity (C), Aspect Ratio (AR), Roundness (R), and Solidity (S) in the seed types considered according to their tubercle shape.Different superscript letters in the same column indicate significant differences from Campbell and Skillings analysis (p < 0.05).

Table 9 .
Tubercle measurements.Mean values (coefficient of variation) for each seed type in the measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tubercle curvature (MaxIntCurv), tubercle width, tubercle height, and slope.Different superscript letters in the same column indicates significant differences from Campbell and Skillings analysis (p < 0.05).N indicates the number of tubercles measured in each group.

Table 9 .
Tubercle measurements.Mean values (coefficient of variation) for each see measurements of maximum tubercle curvature (MaxTubCurv), maximum inter-tuber (MaxIntCurv), tubercle width, tubercle height, and slope.Different superscript letter column indicates significant differences from Campbell and Skillings analysis (p < 0.05 the number of tubercles measured in each group.

Table A4 .
General morphological measurements corresponding to the two species of Group 4.

Table A6 .
General morphological measurements corresponding to the three species of Group 6.A = Area; P = Perimeter; L = Length; W = Width; C = Circularity; AR = Aspect Ratio; R = Roundness; S = Solidity.