## 3 Results
### Micromorphological Characteristics  
Examination of seeds using a scanning electron microscope revealed remarkable variation in surface patterns (Table 3 and Figure 5). We categorized seeds into three major types (Types I, II, and III) based on their ornamentation, epidermal cell pattern, and the shape of the anticlinal and periclinal cell walls. Each type was further categorized into two subtypes. The epidermal cell shape was irregular, rounded, isodiametric, or tetra-to-polygonal. The boundary of the anticlinal cell wall was almost indistinct in some seeds, but it was raised in others. Anticlinal cell walls were straight or slightly sinuous, thick or thin, and with a surface that was either smooth or possessed fine folds or coarse folded papillae. Periclinal cell walls showed a large variation among species, ranging from concave to strongly convex, with a surface that was either smooth with globular central tuberculae or coarse with folded central papillae. Figure 5: Scanning electron microscope micrographs showing (**A,C,E,G,I,K**) an overview of the seed surface and (**B,D,F,H,J,L**) detailed seed ornamentation. (**A,B**) _Descurainia sophia_ (Type I-1; simple reticulate); (**C,D**) _Lepidium apetatum_ (Type III-1; reticulate-papillate); (**E,F**) _Drabu memorosa_ (Type I-2; simple reticulate); (**G,H**) _Erysimum cheiranthoides_ (Type II-1; reticulate-tuberculae); (**I,J**) _Erysimum macilentum_ (Type II-2; reticulate-tuberculae); (**K,L**) _Lepidium virginicum_ (Type III-1; reticulate-papillate). WA: wing-like appendage. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  
Type I seeds included those of _De. sophia_ and _Dr. memorosa_. These seeds showed simple reticulate ornamentation with a raised, thick anticlinal cell wall and a concave, smooth periclinal cell wall (Figure 5A,B,E,F). The reticulate ornamentation of Type I seeds was divided into two subtypes (Type I-1 and Type I-2), based on the epidermal cell pattern and anticlinal cell wall surface. Seeds of _De. sophia_ were designated as Type I-1 and they showed an irregular, rounded, or polygonal epidermal cell pattern; the surface of the anticlinal wall was either smooth or had fine folds (Figure 5B). Seeds of _Dr. memorosa_ were categorized as Type I-2, with an isodiametric or tetra-to-hexagonal epidermal cell pattern; the surface of the anticlinal wall was either smooth or coarse with folded papillae (Figure 5F). Type II seeds included those of _E. cheiranthoides_ and _E. macilentum_. These seeds showed reticulate-tuberculate ornamentation, with a straight, thick, smooth-to-fine folded anticlinal cell wall and a convex, radiate-striate periclinal cell wall with globular central tuberculae (Figure 5G-J). The reticulate-tuberculate ornamentation of Type II seeds was further divided into two subtypes (Type II-1 and Type II-2), which were based on the degree of anticlinal cell wall and the diameter of the tuberculae. _E. cheiranthoides_ seeds were designated as Type II-1; these possessed a slightly raised anticlinal cell wall and a convex periclinal cell wall with narrow tuberculae (5.0-9.2 um in diameter; average = 6.9 um) (Figure 5H). Seeds of _E. macilentum_ were categorized as Type II-2; these seeds exhibited a raised anticlinal cell wall and a strongly convex periclinal cell wall with wide tuberculae (9.1-17.2 um in diameter; average = 12.4 um) (Figure 5J). Type III seeds included those of _L. apetalum_ and _L. virginicum_. These seeds showed reticulate-papillate ornamentation with an isodiametric or polygonal epidermal cell pattern. The anticlinal wall was straight and thin, with a smooth or finely folded surface, and the periclinal cell wall was radiate-striate with coarse folded central papillae (Figure 5C,D,K,L). The reticulate-papillate ornamentation of Type III seeds was divided into two subtypes (Type III-1 and Type III-2), based on the degree of anticlinal cell wall and the diameter of papillae. Type III-1 seeds were observed in _L.