I bought the vegetation pack 1. http://www.dexsoft-games.com/bundles/vegetation1.html
This is what I got as an example of oak2 folder.
15/05/2008 19:28 355,480 oak1_bw.tga
23/03/2008 10:35 1,358,741 oak1_c.tga
25/03/2008 15:50 1,388,477 oak1_n.tga
15/05/2008 19:28 142,014 oak1_o2.tga
23/03/2008 10:54 142,014 oak1_op.tga
15/05/2008 19:27 361,494 oak1_sp.tga
15/05/2008 20:45 298,608 oak2_lod.png
17/05/2008 11:43 100,997 oak2_lod.tga
16/05/2008 11:16 40,654 oak_2.3ds
18/05/2008 17:01 38,100 oak_2.b3d
18/04/2009 11:04 87,091 oak_2.dae
18/04/2009 11:04 203,408 oak_2.fbx
18/04/2009 10:45 53,502 oak_2.lwo
18/05/2008 17:59 2,839,580 oak_2.mdl
18/05/2008 16:59 109,149 oak_2.ms3d
16/05/2008 11:16 348 oak_2.mtl
16/05/2008 11:16 102,780 oak_2.obj
18/05/2008 17:00 137,024 oak_2.txt
16/05/2008 11:15 156,754 oak_2.x
16/05/2008 11:16 836 oak_2_lod.3ds
18/04/2009 11:05 4,896 oak_2_lod.dae
18/04/2009 11:05 19,376 oak_2_lod.fbx
18/04/2009 11:05 1,338 oak_2_lod.lwo
18/05/2008 18:01 348,676 oak_2_lod.mdl
18/05/2008 17:06 965 oak_2_lod.ms3d
16/05/2008 11:16 329 oak_2_lod.mtl
16/05/2008 11:16 730 oak_2_lod.obj
18/05/2008 17:07 937 oak_2_lod.txt
16/05/2008 11:15 4,381 oak_2_lod.x
15/05/2008 20:47 263,222 o_lod_o2.bmp
15/05/2008 20:48 175,917 o_lod_o2.tga
15/05/2008 20:48 55,855 o_lod_op.tga
Contents of oak2.mtl and shows only the full image.
#
# Wavefront material file
# Converted by the DEEP Exploration Deep Exploration 5 5.0.3.1555 Release
# Right Hemisphere, LTD
# http://www.righthemisphere.com/
#
newmtl oak1Mat
Ka 0 0 0
Kd 1 1 1
Ks 0.0075 0.0075 0.0075
illum 2
Ns 22.6274
map_Kd oak1_c.tga
map_bump
bump
map_opacity
map_d
refl
map_kS
map_kA
map_Ns
The file oak1_c.tga is the full texture and when converting using obj2gmf it produces 1 surface looking for oak1_c.mat
Also I notice if I convert using obj2gmf the tree is on it's side in the scene in model viewer, but correct when converting the fbx versions.
Seems that some trees do have 2 textures, but others not.
Not sure if others have come across these trees yet then I guess.