1. INTRODUCTION 17
18
The genus Camptotheca, including the two tree species C. acuminata(Chinese Happytree) and C. lowreyana[1], is of 19 great medicinal importance because it provides effective medicines against various forms of cancer [2-4]. Some 20 taxonomical studies include the genus in the Cornaceae or Cornaceae s.l. family [5-7], whereas others place it - together 21 with the genus Nyssaand often also with Davidia- in a separate Nyssaceae family [1, 2, 8, 9]. Camptothecais considered 22 to be a relict genus, with more members and a widerdistribution during the Tertiary [3]. 23
24
Currently, Camptotheca is only native in central and southern China (including the province Yunnan that borders …show more content…
1). Pollen samples were collected 59 with depth intervals of ca. 50 cm. Sample preparation included treatment with HCl and KOH, sieving (meshes 120 µm), 60 treatment with HF, acetolysis (7 min), and mountingin silicone oil [20]. Counting was with a Zeiss binocular microscope 61 with a magnification of 400 times; larger magnifications were used for the identification of problematic palynomorphs. 62
63
Example pollen diagrams with selected depth intervals and pollen types are presented in Fig. 2. Pollenand spores were 64 identified with and named after various pollen morphological studies [21-25]. Additionally, a pollen reference collection 65 was used. Observed palynomorphological types are in the text of this paper displayed in SMALL CAPITALS in order to 66 differentiate them clearly from inferred plant taxa[26, 27]. 67
UNDER PEER REVIEW
68
69
Fig. 2. Pollen diagrams of cores HN, HT, and CD – selected types and selected depth levels. 70
Pollen type groups: 1. Types of plant taxa >100 m asl; 2: types of taxa covering broad ecological ranges; 3: types of open 71 water taxa; 4: types of (back-)mangrove taxa; 5: types of riparian taxa. 72 …show more content…
It is not yet 181 possible to estimate accurately how widespread Camptothecamay have been in the Red River Delta, but since its pollen 182 was observed at various sites within the delta the genus must have been common, be it localized and associated with 183 specific succession stages. Low pollen production and poor pollen dispersal (as discussed above) may explain why the 184 pollen type was not found in all cores. 185
186
From the data currently available, the presence of Camptothecaat various localities in the Red River Delta is evident for 187 the time-slice between ca. 6500 and 5300 cal yr BP.The genus probably also occurred during 7400-6500 cal yr BP and 188 between 1400-250 cal yr BP. It is very likely that the taxon also occurred during other time-slices, but hard conclusions 189 cannot be drawn from the data currently available. The palaeoecological record does not provide much indication on why 190
Camptothecais currently absent from the delta, but its occurrence up to a few centuries ago make it tempting to assume 191 anthropogenic impact as a cause. 192
193
4. CONCLUSION 194
18
The genus Camptotheca, including the two tree species C. acuminata(Chinese Happytree) and C. lowreyana[1], is of 19 great medicinal importance because it provides effective medicines against various forms of cancer [2-4]. Some 20 taxonomical studies include the genus in the Cornaceae or Cornaceae s.l. family [5-7], whereas others place it - together 21 with the genus Nyssaand often also with Davidia- in a separate Nyssaceae family [1, 2, 8, 9]. Camptothecais considered 22 to be a relict genus, with more members and a widerdistribution during the Tertiary [3]. 23
24
Currently, Camptotheca is only native in central and southern China (including the province Yunnan that borders …show more content…
1). Pollen samples were collected 59 with depth intervals of ca. 50 cm. Sample preparation included treatment with HCl and KOH, sieving (meshes 120 µm), 60 treatment with HF, acetolysis (7 min), and mountingin silicone oil [20]. Counting was with a Zeiss binocular microscope 61 with a magnification of 400 times; larger magnifications were used for the identification of problematic palynomorphs. 62
63
Example pollen diagrams with selected depth intervals and pollen types are presented in Fig. 2. Pollenand spores were 64 identified with and named after various pollen morphological studies [21-25]. Additionally, a pollen reference collection 65 was used. Observed palynomorphological types are in the text of this paper displayed in SMALL CAPITALS in order to 66 differentiate them clearly from inferred plant taxa[26, 27]. 67
UNDER PEER REVIEW
68
69
Fig. 2. Pollen diagrams of cores HN, HT, and CD – selected types and selected depth levels. 70
Pollen type groups: 1. Types of plant taxa >100 m asl; 2: types of taxa covering broad ecological ranges; 3: types of open 71 water taxa; 4: types of (back-)mangrove taxa; 5: types of riparian taxa. 72 …show more content…
It is not yet 181 possible to estimate accurately how widespread Camptothecamay have been in the Red River Delta, but since its pollen 182 was observed at various sites within the delta the genus must have been common, be it localized and associated with 183 specific succession stages. Low pollen production and poor pollen dispersal (as discussed above) may explain why the 184 pollen type was not found in all cores. 185
186
From the data currently available, the presence of Camptothecaat various localities in the Red River Delta is evident for 187 the time-slice between ca. 6500 and 5300 cal yr BP.The genus probably also occurred during 7400-6500 cal yr BP and 188 between 1400-250 cal yr BP. It is very likely that the taxon also occurred during other time-slices, but hard conclusions 189 cannot be drawn from the data currently available. The palaeoecological record does not provide much indication on why 190
Camptothecais currently absent from the delta, but its occurrence up to a few centuries ago make it tempting to assume 191 anthropogenic impact as a cause. 192
193
4. CONCLUSION 194