| Habit | Diffuse, perennial herb | Prostrate, perennial
herbs | Ornamental perennial
climber | Erect, branching,
annual herb |
| Stem structure | | | | |
| Length | 8–10 branches, from
central stock (35–40 cm) | Several prostrate
stems (10–30 cm) | 20–45 cm, splintery,
fibrous | 20–60 cm, opposite
decussate branches |
| Surface | Pubescent | Clothed with silky hairs | Smooth | Glabrous |
| Internodes | 7–10 mm | 10–12 mm | 6–13 cm | Usually 3.5–4.5 cm, up to 6.2 cm |
| Taste | Tasteless | Tasteless | Bitter | Bitter |
| Outline in T.S. | Terete, wings absent | Terete, wings absent | Terete, wings absent | Annular with four wings |
| Cuticle | Ridged | Striated | Ridged | Ridged |
| Trichomes covering | Present,unequally
biarmed | Present, conical, unicellular | Present, with two basal cells, multicellular | Absent |
| Glandular | Present, stalk unicellular, head multicellular (8–
10 cells in 2–4 tiers) | Present, stalk unicellular,
head multicellular
(four cells) | Present, stalk multicellular, head unicellular | Absent |
| Chlorenchyma | Present | Present | Present | Absent |
| Collenchyma | Present | Present | Present | Absent |
| Endodermis | Indistinct | Indistinct | Indistinct | Distinct |
| Pericyclic fibers | Present | Present | Present | Absent |
| Phloem fibers | Absent | Present in old stem only | Present | Absent |
| Pith | Core hollow | Often an angular hollow, cells pitted in older stem | Pitted with slopting end | Intact, cells pitted when mature |
| Leaf structure | | | | |
| Phyllotaxy | Alternate | Alternate | Opposite | Opposite decussate |
| Shape | Elliptic-oblong | Linear, lower Oblanc-
eolate,upper elliptic | Imparipinnate, ovate or oblong | Oblong, lanceolate |
| Size | (8–12) mm×
(5–7) mm | (12–38) mm×
(5–10) mm | (2–5) cm×
(1–2) cm | (25–38) mm×
(8–15) mm |
| Apex | Mucronate | Obtuse-muronate | Mucronate | Acute |
| Surface | Pubescent | Hairy | Hairy | Glabrous |
| Midrib | | | | |
| Outline in T.S. | Plano-convex, dorsal
bulge prominent | Concavo-convex | Concavo-convex,
dorsiventral | Concavo-convex, dorsal
bulge irregularly lobed |
| Collenchyma | Present on either side | Present beneath
upper epidermis | – | Absent on either side |
| Calcium oxalate | Present as rosette | Plenty, along veins | Prismatic crystal along
veins | Absent |
| Lamina | Isobilateral, palisade in
2 layers on either side | Isobilateral, palisade in 3
and 2 layers beneath upper and lower epidermis respectively | Dorsiventral, palisade in either side | Dorsiventral, palisade in 1 layer |
| Cuticle | Striated | Striated | Striated, weavy | Ridged |
| Trichomes | Present, similar as in stem | Present, similar as in stem | Present, similar as in stem | Absent |
| Stomata | Both anisocytic and paracytic types on either side | Both anisocytic and
paracytic types on
either side | Subcoriaceous, rubiaceous
stomata with wavy cells
present on both side | Anisocytic; upper
epidermis has a few
stomata |
| Quantitative analysis | | | | |
| Stomatal number | | | | |
| Upper surface | 280–328–405 | 202–216–238 | 291–342–411 | Very few |
| Lower surface | 270–336–424 | 184–212–248 | 188–223–251 | 52–72–108 |
| Stomatal index | | | | |
| Upper surface | 14.5–15.5–16.5 | 17.0–18.0–19.9 | 16.9–18.0–19.1 | Very few |
| Lower surface | 15.7–17.0–18.7 | 13.8–15.8–16.9 | 14.8–16.3–17.2 | 16.9–21.0–24.6 |
| Vein-islet number | 18.0–19.0–20.0 | 21.0–23.0–25.0 | 7.5–8.0–9.0 | 1–2.5–3.25 |
| Extractive value (w/w, %) | | | | |
| Water soluble | 19.80 | 17.08 | 18.21 | 10.00 |
| Alcohol soluble | 18.20 | 14.04 | 16.14 | 13.92 |