Table 2.
Overview of selected wood anatomical characters within Spermacoceae and Knoxieae (Rubiaceae). Species are arranged alphabetically according to the tribal studies of Groeninckx et al. (2009a) and Kårehed and Bremer (2007). Numbers between hyphens are mean values flanked by minimum and maximum values. For specimens of the same taxon, superscript numbers after the species name refer to the order of the specimens as followed in the species list (see Appendix). Species names in bold represent underground woody organs, and juvenile wood samples are marked with an asterisk behind the species names
| Species studied | Primarily or secondarily woody | Length vs. age curve | Tendency to (semi-)ringporosity | Solitary vessels | Radial vessel multiples | Tangential vessel multiples | Vessel clusters | Vessel diameter (μm) | Vessel density (mm−1) | Vessel element length (μm) | Tracheid length (μm) | Tracheids thick-walled | Occasional septate libriform fibres | Dif axial parenchyma | Dia axial parenchyma | Banded axial parenchyma | Scanty axial parenchyma | Rays absent | Rays exclusively uniseriate | Multiseriate ray width (no. cells) | Multiseriate ray height (μm) | Ray cells mostly or all square-to-upright |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Spermacoceae | ||||||||||||||||||||||
| Arcytophyllum lavarum* | S | Flat | − | + | + | − | − | 15–20–30 | 100–125–160 | 150–195–250 | 250–300–350 | − | − | ± | − | − | ± | − | + | / | / | + |
| Arcytophyllum setosum | S | Decr | − | + | + | − | − | 15–20–25 | 80–100–140 | 150–290–400 | 300–370–450 | − | − | − | − | − | − | + | C | / | / | / |
| Arcytophyllum thymifolium* | S | Flat | − | + | + | − | − | 10–16–20 | 480–540–640 | 100–160–250 | 150–200–250 | − | − | + | − | − | + | − | + | / | / | + |
| Diodella sarmentosa | S | Flat | − | ± | ± | + | ± | 25–60–120 | 36–48–66 | 150–300–550 | 350–465–550 | − | − | − | ± | − | + | − | − | 2–14 | 200–2130–8000 | + |
| Emmeorhiza umbellata* | S | Decr | − | + | − | − | − | 15–55–120 | 60–81–85 | 200–350–500 | 500–610–700 | − | + | − | ± | − | + | − | + | / | / | + |
| Gomphocalyx herniarioides | S | Decr | − | + | ± | − | − | 15–28–40 | 135–150–180 | 100–160–250 | 250–340–400 | − | − | − | ± | − | ± | − | − | 2–3 | 300–840–1500 | + |
| Hedyotis flavescens* | S | Decr | − | + | − | − | − | 10–23–30 | 90–110–140 | 300–650–850 | 750–910–1150 | − | + | ± | − | − | ± | − | + | / | / | + |
| Hedyotis fruticosa* | S | Decr | − | + | ± | − | − | 25–36–50 | 80–95–120 | 250–480–700 | 600–765–900 | − | + | ± | − | − | ± | − | + | / | / | + |
| Hedyotis lessertiana* | S | Flat | − | + | ± | − | − | 15–25–30 | 75–45–120 | 300–660–1000 | 850–1050–1300 | − | + | − | − | − | − | − | + | / | / | + |
| ‘Hedyotis’trichoglossa | S | Decr | − | + | ± | − | − | 15–21–30 | 100–120–145 | 300–540–700 | 500–665–800 | − | + | − | − | − | − | − | + | / | / | + |
| Kadua cordata | S | Flat | − | + | ± | − | − | 20–29–50 | 140–170–230 | 350–450–700 | 500–630–800 | − | + | ± | − | − | ± | − | + | / | / | + |
| Lathraeocarpa acicularis | S | Decr | + | + | − | ± | ± | 10–21–40 | 200–255–290 | 100–220–300 | 400–470–600 | ± | − | − | ± | − | + | − | + | / | / | + |
| Mitracarpus frigidus | S | Flat | ± | + | ± | ± | − | 15–25–45 | 140–170–200 | 250–375–550 | 550–690–850 | − | + | ± | − | − | ± | − | − | 2 | 150–345–650 | + |
| Nesohedyotis arborea1 | S | Flat | − | + | + | − | − | 20–50–80 | 16–20–25 | 200–340–500 | 600–750–900 | − | − | − | + | − | ± | − | − | 4–6 | 300–550–900 | ± |
| ‘Oldenlandia’ ambovombensis1* | S | Flat | + | + | − | − | − | 10–19–40 | 240–265–300 | 150–300–450 | 350–485–600 | ± | − | ± | − | − | + | − | + | / | / | + |
| ‘Oldenlandia’ ambovombensis2 | S | Flat | + | + | − | − | − | 10–20–40 | 260–285–320 | 150–275–350 | 400–460–550 | ± | − | ± | − | − | + | − | + | / | / | + |
| ‘Oldenlandia’ humbertii* | S | Flat | ± | + | − | − | − | 10–19–30 | 290–325–380 | 100–200–300 | 300–405–500 | + | − | − | − | − | + | − | + | / | / | + |
| Spermacoceae bangweolensis | S | Flat | − | + | + | − | − | 20–30–45 | 110–125–160 | 150–320–400 | 350–500–650 | − | − | − | ± | − | ± | − | − | 2 | 200–300–550 | + |
| Spermacoce macrocephala | S | Flat | − | + | − | ± | − | 15–26–35 | 110–140–160 | 450–690–950 | 650–840–950 | − | − | ± | − | − | ± | − | − | 2 | 600–950–1800 | + |
| Spermacoce manikensis | S | Flat | − | + | ± | ± | ± | 15–23–30 | 100–115–130 | 100–300–500 | 500–605–800 | − | + | − | ± | − | ± | − | + | / | / | + |
| Spermacoce occidentalis | S | Flat | − | + | ± | − | − | 20–35–50 | 120–140–160 | 200–350–450 | 350–460–550 | − | − | − | ± | − | + | − | − | 2–3 | 200–400–700 | + |
| Spermacoce verticillata1 | S | Decr | − | + | ± | − | ± | 15–22–30 | 120–160–190 | 300–415–550 | 500–640–800 | − | + | ± | − | − | ± | − | + | / | / | + |
| Spermacoce verticillata2 | S | Decr | ± | + | ± | − | ± | 15–30–45 | 130–145–170 | 150–240–500 | 400–495–600 | − | + | ± | − | − | ± | − | − | 2 | 300–440–600 | + |
| Knoxieae | ||||||||||||||||||||||
| Carphalea kirondron* | P | Norm | ± | + | ± | − | ± | 25–55–100 | 60–72–85 | 300–410–550 | 600–720–850 | − | − | − | + | ± | + | − | − | 2–3 | 300–565–1000 | − |
| Dirichletia virgata | P | Norm | ± | − | ± | − | + | 20–40–70 | 60–75–85 | 150–330–500 | 850–1045–1200 | − | − | − | + | − | + | − | − | 3–4 | 250–410–600 | − |
| Otiophora rupicola* | S | Flat | − | + | ± | − | − | 15–20–30 | 140–160–180 | 300–450–600 | 400–575–700 | − | − | ± | − | − | ± | − | − | 2–3 | 100–520–1100 | + |
| Otomeria micrantha | S | Flat | − | + | + | − | − | 15–22–30 | 210–240–280 | 450–680–1100 | 700–840–950 | − | − | − | − | − | − | − | + | / | / | + |
| Pentanisia schweinfurtii1 | S | Decr | − | + | + | − | − | 20–29–50 | 200–215–240 | 150–285–400 | 400–525–650 | − | − | − | + | + | − | − | − | 2–3 | 400–760–1850 | + |
| Pentanisia schweinfurtii2* | S | Decr | − | + | + | − | − | 15–35–75 | 100–135–160 | 150–270–350 | 300–380–450 | − | − | − | + | + | − | − | − | 2–8 | 600–2060–4500 | + |
| Pentas zanzibarica | S | Flat | ± | + | + | − | − | 15–30–50 | 140–180–185 | 200–390–600 | 600–725–800 | − | − | ± | − | − | ± | − | − | 2–4 | 200–720–1600 | + |
| Phyllopentas schimperiana* | S | Decr | ± | + | − | − | − | 20–30–50 | 90–105–120 | 250–450–650 | 550–680–800 | − | − | ± | − | − | ± | − | − | 2–3 | 600–760–1500 | + |
| Triainolepis polyneura | P | Norm | ± | − | + | − | + | 25–65–130 | 25–32–38 | 300–490–650 | 800–1020–1200 | − | − | − | ± | + | − | − | − | 2–3 | 200–400–600 | − |
Dif, diffuse; Dia, diffuse-in-aggregates; P, primarily woody; S, secondarily woody; Decr, decreasing length vs. age curve; Flat, flat length vs. age curve; Norm, normal length vs. age curve; +, present; ± , sometimes present; −, absent; / indicates not applicable.