Table 2.

Similarity index of the 28 commercial rhubarb samples

	S1	S2	S3	S4	S5	S6	S7	S8	S9	S10	S11	S12	S13	S14	S15	S16	S17	S18	S19	S20	S21	S22	S23	S24	S25	S26	S27	S28
S1	1	0.673	0.614	0.105	0.916	0.548	0.6	0.611	0.843	0.651	0.837	0.669	0.661	0.686	0.359	0.662	0.653	0.713	0.635	0.688	0.682	0.321	0.719	0.855	0.956	0.368	0.713	0.172
S2	0.673	1	0.76	0.123	0.696	0.794	0.908	0.938	0.81	0.96	0.803	0.953	0.859	0.929	0.388	0.943	0.961	0.917	0.957	0.955	0.896	0.271	0.946	0.468	0.655	0.551	0.923	0.253
S3	0.614	0.76	1	0.173	0.746	0.776	0.816	0.709	0.614	0.783	0.905	0.682	0.846	0.826	0.379	0.673	0.688	0.624	0.746	0.711	0.745	0.306	0.716	0.542	0.578	0.637	0.737	0.302
S4	0.105	0.123	0.173	1	0.145	0.127	0.144	0.104	0.105	0.126	0.161	0.101	0.131	0.125	0.106	0.104	0.102	0.088	0.114	0.108	0.122	0.099	0.108	0.113	0.099	0.147	0.109	0.127
S5	0.916	0.696	0.746	0.145	1	0.574	0.615	0.618	0.794	0.669	0.926	0.636	0.753	0.696	0.484	0.616	0.64	0.667	0.631	0.666	0.672	0.409	0.697	0.902	0.924	0.444	0.713	0.248
S6	0.548	0.794	0.776	0.127	0.574	1	0.928	0.849	0.659	0.897	0.749	0.844	0.841	0.885	0.399	0.798	0.795	0.725	0.868	0.811	0.888	0.326	0.832	0.395	0.464	0.668	0.825	0.242
S7	0.6	0.908	0.816	0.144	0.615	0.928	1	0.919	0.744	0.97	0.8	0.94	0.86	0.97	0.377	0.912	0.916	0.863	0.952	0.92	0.95	0.279	0.934	0.378	0.527	0.667	0.923	0.234
S8	0.611	0.938	0.709	0.104	0.618	0.849	0.919	1	0.83	0.963	0.758	0.966	0.874	0.946	0.345	0.965	0.971	0.925	0.982	0.957	0.881	0.245	0.96	0.366	0.578	0.525	0.956	0.229
S9	0.843	0.81	0.614	0.105	0.794	0.659	0.744	0.83	1	0.808	0.815	0.858	0.791	0.839	0.497	0.874	0.853	0.907	0.828	0.881	0.779	0.443	0.885	0.644	0.813	0.471	0.894	0.222
S10	0.651	0.96	0.783	0.126	0.669	0.897	0.97	0.963	0.808	1	0.812	0.972	0.884	0.976	0.41	0.951	0.968	0.921	0.983	0.966	0.953	0.299	0.972	0.437	0.607	0.624	0.956	0.244
S11	0.837	0.803	0.905	0.161	0.926	0.749	0.8	0.758	0.815	0.812	1	0.761	0.871	0.851	0.509	0.745	0.759	0.75	0.779	0.785	0.789	0.412	0.804	0.763	0.813	0.585	0.827	0.276
S12	0.669	0.953	0.682	0.101	0.636	0.844	0.94	0.966	0.858	0.972	0.761	1	0.837	0.956	0.389	0.98	0.982	0.967	0.982	0.98	0.921	0.283	0.983	0.408	0.621	0.538	0.968	0.202
S13	0.661	0.859	0.846	0.131	0.753	0.841	0.86	0.874	0.791	0.884	0.871	0.837	1	0.917	0.426	0.819	0.832	0.779	0.865	0.838	0.83	0.349	0.856	0.575	0.676	0.528	0.887	0.287
S14	0.686	0.929	0.826	0.125	0.696	0.885	0.97	0.946	0.839	0.976	0.851	0.956	0.917	1	0.381	0.944	0.949	0.917	0.97	0.958	0.936	0.298	0.965	0.469	0.642	0.603	0.966	0.245
S15	0.359	0.388	0.379	0.106	0.484	0.399	0.377	0.345	0.497	0.41	0.509	0.389	0.426	0.381	1	0.333	0.37	0.397	0.355	0.406	0.462	0.784	0.428	0.502	0.364	0.501	0.433	0.192
S16	0.662	0.943	0.673	0.104	0.616	0.798	0.912	0.965	0.874	0.951	0.745	0.98	0.819	0.944	0.333	1	0.979	0.959	0.978	0.983	0.891	0.242	0.968	0.371	0.609	0.522	0.947	0.208
S17	0.653	0.961	0.688	0.102	0.64	0.795	0.916	0.971	0.853	0.968	0.759	0.982	0.832	0.949	0.37	0.979	1	0.972	0.981	0.98	0.903	0.258	0.981	0.402	0.625	0.524	0.965	0.213
S18	0.713	0.917	0.624	0.088	0.667	0.725	0.863	0.925	0.907	0.921	0.75	0.967	0.779	0.917	0.397	0.959	0.972	1	0.939	0.966	0.863	0.31	0.97	0.455	0.686	0.479	0.961	0.183
S19	0.635	0.957	0.746	0.114	0.631	0.868	0.952	0.982	0.828	0.983	0.779	0.982	0.865	0.97	0.355	0.978	0.981	0.939	1	0.977	0.913	0.259	0.971	0.381	0.587	0.575	0.956	0.232
S20	0.688	0.955	0.711	0.108	0.666	0.811	0.92	0.957	0.881	0.966	0.785	0.98	0.838	0.958	0.406	0.983	0.98	0.966	0.977	1	0.915	0.307	0.98	0.446	0.649	0.556	0.959	0.232
S21	0.682	0.896	0.745	0.122	0.672	0.888	0.95	0.881	0.779	0.953	0.789	0.921	0.83	0.936	0.462	0.891	0.903	0.863	0.913	0.915	1	0.339	0.943	0.493	0.613	0.649	0.906	0.235
S22	0.321	0.271	0.306	0.099	0.409	0.326	0.279	0.245	0.443	0.299	0.412	0.283	0.349	0.298	0.784	0.242	0.258	0.31	0.259	0.307	0.339	1	0.315	0.444	0.328	0.597	0.349	0.193
S23	0.719	0.946	0.716	0.108	0.697	0.832	0.934	0.96	0.885	0.972	0.804	0.983	0.856	0.965	0.428	0.968	0.981	0.97	0.971	0.98	0.943	0.315	1	0.483	0.68	0.559	0.983	0.22
S24	0.855	0.468	0.542	0.113	0.902	0.395	0.378	0.366	0.644	0.437	0.763	0.408	0.575	0.469	0.502	0.371	0.402	0.455	0.381	0.446	0.493	0.444	0.483	1	0.916	0.303	0.493	0.203
S25	0.956	0.655	0.578	0.099	0.924	0.464	0.527	0.578	0.813	0.607	0.813	0.621	0.676	0.642	0.364	0.609	0.625	0.686	0.587	0.649	0.613	0.328	0.68	0.916	1	0.278	0.688	0.182
S26	0.368	0.551	0.637	0.147	0.444	0.668	0.667	0.525	0.471	0.624	0.585	0.538	0.528	0.603	0.501	0.522	0.524	0.479	0.575	0.556	0.649	0.597	0.559	0.303	0.278	1	0.548	0.493
S27	0.713	0.923	0.737	0.109	0.713	0.825	0.923	0.956	0.894	0.956	0.827	0.968	0.887	0.966	0.433	0.947	0.965	0.961	0.956	0.959	0.906	0.349	0.983	0.493	0.688	0.548	1	0.213
S28	0.172	0.253	0.302	0.127	0.248	0.242	0.234	0.229	0.222	0.244	0.276	0.202	0.287	0.245	0.192	0.208	0.213	0.183	0.232	0.232	0.235	0.193	0.22	0.203	0.182	0.493	0.213	1
RSI	0.769	0.913	0.81	0.297	0.803	0.84	0.904	0.895	0.885	0.933	0.894	0.912	0.888	0.935	0.545	0.895	0.906	0.892	0.915	0.924	0.909	0.478	0.935	0.622	0.737	0.695	0.932	0.398

Rheum officinale Bail.: S1, S5, S8, S11, S13, S14, S16, S17, S21, S24, S25, S26, S27, S28; Rheum palmatum L.: S2, S6, S7, S10, S18, S19, S23; Rheum tanguticum Maxim. ex Balf.: S3, S4, S9, S12, S15, S20, S22; All the rhubarb samples were examined to create a mean global chromatogram as the standard fingerprint, and the reference similarity index (RSI) of each chromatogram of rhubarb samples against the mean global chromatogram was calculated using the Similarity Evaluation System for Chromatographic Fingerprint of TCM (version 2004). Group A includes sample S2, S7–S14, S16–S21, S23 and S27 (RSI ≥ 0.885; The RSI values of these samples are approximate or higher than 0.9); Group B includes sample S1, S3–S6, S15, S22, S24–S26 and S28 (RSI ≤ 0.84; The RSI values of most of these samples are far less than 0.9)