Table 2.

Phloem sap sugar concentration data. Sugar mass fraction c_i and standard error/range δc_i obtained from reference Ref I using either bleeding (b) or stylectomy (s) protocols, as indicated in column PC. The protocol for determining the loading mechanism (PLM) was based on studies examining plasmodesmata (1), autoradiographs (2), leaf sugar concentration (3), osmolality of leaf sap (4), incipient plasmolysis (5) and sugar transporters (6) from reference Ref II. Whenever possible, species (S)- and genus (G)-level studies were used to infer loading type. For several species loading type was determined based on plant family (F). Index i refers to the position of the species along the coordinate axis in figure 2a.

i	species	common name	ci	(δci)	PC	ref I	loading mechanism	PLM	ref II
1	Brassica oleracea L.	cabbage	4.3		(b)	[53]	active	G(1)	[54]
2	Salix L. sp.	willow	4.8	(1.6)	(s)	[55]	passive	G(1,2,3,5)	[56]
3	Salix viminalis L.	basket willow	5.0	(1.0)	(s)	[37]	passive	G(1,2,3,5)	[56]
4	Humulus lupulus L.	common hops	6.8		(b)	[7]	passive	F(1)	[54]
5	Ricinus communis L.	castor bean	8.3	(1.6)	(b)	[57]	passive	S(1)	[54]
6	Triticum aestivum L.	wheat	8.3		(s)	[39]	active	S(6)	[58]
7	Salix acutifolia Willd	littletree willow	8.4	(0.1)	(s)	[36]	passive	G(1,2,3,5)	[56]
8	Fraxinus americana L.	white ash	8.5	(1.0)	(b)	[29]	active	S(1,2,3)	[59]
9	Ricinus communis L.	castor bean	9.0	(1.0)	(b)	[28]	passive	S(1)	[54]
10	Platanus occidentalis L.	American sycamore	9.6	(0.9)	(b)	[29]	passive	G(1,2,3)	[59]
11	Ricinus communis L.	castor bean	9.9	(1.6)	(b)	[60]	passive	S(1)	[54]
12	Fraxinus pennsylvanica Marshall	green ash	11.1	(0.7)	(b)	[29]	active	G(1,2,3)	[59]
13	Arabidopsis thaliana (L.) Heynh.	mouse-ear cress	11.1	(1.6)	(s)	[61]	active	S(6)	[62]
14	Ricinus communis L.	castor bean	11.4	(3.1)	(b)	[45]	passive	S(1)	[54]
15	Pinus sylvestris L.	scots pine	11.5		(b)	[7]	passive	G(1)	[54]
16	Medicago sativa L.	clover	13.0		(s)	[63]	active	G(1)	[54]
17	Robinia pseudoacacia L.	black locust	13.6	(2.6)	(b)	[64]	active	G(1)	[54]
18	Quercus pedunculata Willd.	pedunculate oak	13.6		(b)	[7]	passive	G(1,2,3,4)	[3]
19	Lupinus albus L.	white lupine	14.0	(4.4)	(b)	[65]	active	G(1)	[54]
20	Arenga pinnata (Wurmb) Merr.	sugar palm	14.1		(b)	[66]	passive	F(1)	[54]
21	Salix viminalis L.	basket willow	15.0	(5.9)	(s)	[67]	passive	G(1,2,3,5)	[56]
22	Nicotiana glauca Graham	tree tobacco	15.1	(0.6)	(b)	[68]	active	G(1,2,3,4)	[3]
23	Carpinus betulus L.	European hornbeam	15.7	(2.0)	(b)	[7]	passive	S(1)	[54]
24	Salix exigua Nutt.	narrowleaf willow	15.9	(3.0)	(s)	[40]	passive	G(1,2,3,5)	[56]
25	Lactuca sativa L.	lettuce	16.0	(2.1)	(s)	[32]	active	F(1,2,3,4)	[3]
26	Castanea sativa Mill.	European chestnut	16.2		(b)	[7]	passive	G(1)	[54]
27	Oryza sativa L. var. Towada	rice	16.5	(0.1)	(s)	[69]	passive	S(1,3,6)	[70]
28	Robinia pseudoacacia L.	black locust	16.5	(2.1)	(b)	[29]	active	G(1)	[54]
29	Tilia platyphyllos Scop.	large-leaved lime	16.8	(0.6)	(b)	[64]	passive	G(1,2,3,4)	[3]
30	Quercus borealis Michx. f.	northern red oak	17.0	(0.5)	(b)	[64]	passive	G(1,2,3,4)	[3]
31	Quercus rubra L.	northern red oak	17.1	(2.3)	(b)	[7]	passive	S(1,2,3,4)	[3]
32	Triticum aestivum L.	wheat	17.2	(0.6)	(s)	[71]	active	S(6)	[58]
33	Acer platanoides L.	Norway maple	17.9	(1.2)	(b)	[64]	passive	G(1,2,3,4)	[3]
34	Tilia L. sp.	basswood	18.5		(b)	[7]	passive	G(1,2,3,4)	[3]
35	Tilia parvifolia Ehrh.	small-leaved lime	19.0		(b)	[7]	passive	G(1,2,3,4)	[3]
36	Oryza sativa L. var. Towada	rice	19.4	(2.9)	(s)	[38]	passive	S(1,3,6)	[70]
37	Acer pseudoplatanus L.	sycamore maple	20.6	(3.2)	(b)	[7]	passive	G(1,2,3,4)	[3]
38	Fraxinus americana L.	white ash	22.1	(1.1)	(b)	[72]	active	S(1,2,3)	[59]
39	Brassica nigra (L.) W. D. J. Koch	black mustard	22.5	(3.5)	(s)	[73]	active	G(1)	[54]
40	Robinia pseudoacacia L	black locust	22.8	(5.1)	(b)	[7]	active	G(1)	[54]
41	Lupinus mutabilis Sweet	Tarwi	24.0	(4.0)	(b)	[30]	active	G(1)	[54]
42	Avena sativa L.	common oat	24.6	(1.7)	(s)	[74]	active	F(1)	[54]
43	Spinacia oleracea L.	spinach	24.6		(s)	[75]	active	S(3)	[76]
44	Fraxinus americana L.	white ash	25.0	(2.0)	(b)	[64]	active	S(1,2,3)	[59]
45	Eucalyptus globulus Labill.	Tansmanian bluegum	25.1	(4.0)	(b)	[77]	active	G(1,3)	[54,78]
46	Acer platanoides L.	Norway maple	25.2		(b)	[7]	passive	G(1,2,3,4)	[3]
47	Zea mays L.	maize	25.8	(6.0)	(s)	[79]	active	S(1,3,5)	[80,81]
48	Tanacetum vulgare L.	tansy	26.8	(13.9)	(s)	[45]	active	F(1,2,3,4)	[3]
49	Zea mays L.	maize	27.4		(s)	[82]	active	S(1,3,5)	[80,81]
50	Hordeum vulgare L.	barley	31.0	(5.0)	(s)	[83]	active	S(1,3)	[76,84]
51	Lolium perenne L.	ryegrass	31.3		(s)	[31]	active	S(1,3,5,6)	[31,85]
52	Prunus persica L.	peach	37.9	(13)	(s)	[86]	passive	S(1,2,3)	[59]
53	Solanum tuberosum L. cv. Desiree	potato	38.1	(2.0)	(s)	[87]	active	S(1,2,3)	[59]
54	Zea mays L.	maize	40.7		(s)	[81]	active	S(1,3,5)	[80,81]
55	Solanum tuberosum L. cv. Desiree	potato	50.4	(3.0)	(s)	[46]	active	S(1,2,3)	[59]