After Earle, 2002

<==o Picea A. Dietrich 1824 (kuuset; spruces) [33 sp.]
   |-- P. abies (Linnaeus) Karsten 1881 (kuusi; North European spruce, common spruce)
   |-- P. alcoquiana (Veitch ex Lindl.) Carrière
   |-- P. asperata Masters 1906 (lohikäärmekuusi; Dragon spruce)
   |-- P. brachytyla (Franch.) Pritzel (Sargent spruce)
   |-- P. breweriana S. Watson 1885 (Weeping or Brewer's spruce )
   |-- P. chihuahuana Martínez 1942 (Chihuahua spruce)
   |-- P. crassifolia Komarov (Qinghai spruce)
   |-- P. engelmannii Parry ex Engelmann 1863 (hopeakuusi; Engelmann spruce, silver spruce, white spruce, mountain spruce)
   |-- P. farreri Page & Rushforth (Farrer spruce)
   |-- P. glauca (Moench) Voss 1907 (White spruce, Canada spruce, skunk spruce, cat spruce, single spruce )
   |-- P. glehnii
   |-- P. jezoensis (Sieb. & Zucc.) Carrière (Yezo spruce)
   |-- P. koraiensis Nakai (Korean spruce)
   |-- P. koyamai Shiras. 1913
   |-- P. likiangensis (Franch.) Pritzel (Lijiang spruce)
   |-- P. mariana (Miller) Britton Sterns, & Poggenburg 1888 (Black spruce, bog spruce, swamp spruce)
   |-- P. maxomowiczii
   |-- P. meyeri Rehder & Wilson (Meyer spruce)
   |-- P. morrisonicola Hayata 1908 (Taiwan spruce)
   |-- P. neoveitchii Masters (Veitch spruce, Hubei spruce)
   |-- P. obovata Ledeb. 1833 (siperiankuusi; Siberian spruce
   |-- P. omorika (Panèiæ) Purkyne 1877 (serbiankuusi; Serbian spruce)
   |-- P. orientalis (Linnaeus) Link (kaukasiankuusi; Oriental spruce, Caucasian spruce)
   |-- P. pungens Engelmann 1879 (Blue spruce, Colorado blue spruce, white spruce, silver spruce, Parry spruce)
   |-- P. purpurea Mast. 1906
   |-- P. retroflexa 
   |-- P. rubens Sargent 1898 (punakuusi; Red spruce, eastern spruce, yellow spruce)
   |-- P. schrenkiana Fisch. & C.A. Mey 1842
   |-- P. sitchensis (Bongard) Carrière 1855 (sitkakuusi; Sitka spruce, tideland spruce, coast spruce, Menzies spruce)
   |-- P. smithiana (Wall.) Boiss. 1884 (raikuusi; Rai Spruce)
   |-- P. spinulosa (Griff.) A. Henry 1906
   |-- P. torano (Siebold ex K.Koch) Koehne 1893
   `-- P. wilsonii Mast. 1903

Reference(s):