System for packaging and applying a cosmetic product, comprising: - a reservoir intended to contain said cosmetic product and having a neck defining a longitudinal axis, and - an applicator device comprising: * a body designed to be held in the hand; * an applicator head (10, 10'); * a wand connecting the body and the applicator head (10, 10'), said body being designed to close said reservoir and the wand being designed to penetrate said reservoir when said body is closing said reservoir; the applicator head (10, 10') comprising: * a main body (11, 11') defining a longitudinal axis and comprising a storage portion (110, 110', 110") designed to be loaded with product and an application portion (111, 112, 111', 112') designed for applying the product, passages (113, 113') being provided between said storage portion (110, 110', 110") and said application portion (111, 112, 111', 112'), the storage portion comprising a groove (110, 110', 110") having a main portion (114, 115, 114', 115', 114", 115") defining an axial extension (E1, E2, E1', E2', E1", E2"), the main body (11, 11') of the head (10, 10') having a certain length (L, L') along the longitudinal axis and the main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110") extending across a major part of said length (L, L') of the main body (11, 11'); * a heating device (12, 12') designed to heat the cosmetic product loaded on the applicator head (10, 10'), the heating device comprising a heating element (120, 120', 120") extending through the inside of said groove (110, 110', 110"), the heating element comprising a resistance wire (120, 120', 120") having a main portion (121, 122, 121', 122', 121", 122") extending along the axis of extension (E1, E2, E1', E2', E1", E2") of the main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110") across the entire length of said main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110"). - a reservoir intended to contain said cosmetic product and having a neck defining a longitudinal axis, and - an applicator device comprising: * a body designed to be held in the hand; * an applicator head (10, 10'); * a wand connecting the body and the applicator head (10, 10'), said body being designed to close said reservoir and the wand being designed to penetrate said reservoir when said body is closing said reservoir; the applicator head (10, 10') comprising: * a main body (11, 11') defining a longitudinal axis and comprising a storage portion (110, 110', 110") designed to be loaded with product and an application portion (111, 112, 111', 112') designed for applying the product, passages (113, 113') being provided between said storage portion (110, 110', 110") and said application portion (111, 112, 111', 112'), the storage portion comprising a groove (110, 110', 110") having a main portion (114, 115, 114', 115', 114", 115") defining an axial extension (E1, E2, E1', E2', E1", E2"), the main body (11, 11') of the head (10, 10') having a certain length (L, L') along the longitudinal axis and the main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110") extending across a major part of said length (L, L') of the main body (11, 11'); * a heating device (12, 12') designed to heat the cosmetic product loaded on the applicator head (10, 10'), the heating device comprising a heating element (120, 120', 120") extending through the inside of said groove (110, 110', 110"), the heating element comprising a resistance wire (120, 120', 120") having a main portion (121, 122, 121', 122', 121", 122") extending along the axis of extension (E1, E2, E1', E2', E1", E2") of the main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110") across the entire length of said main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110"). * a body designed to be held in the hand; * an applicator head (10, 10'); * a wand connecting the body and the applicator head (10, 10'), said body being designed to close said reservoir and the wand being designed to penetrate said reservoir when said body is closing said reservoir; the applicator head (10, 10') comprising: * a main body (11, 11') defining a longitudinal axis and comprising a storage portion (110, 110', 110") designed to be loaded with product and an application portion (111, 112, 111', 112') designed for applying the product, passages (113, 113') being provided between said storage portion (110, 110', 110") and said application portion (111, 112, 111', 112'), the storage portion comprising a groove (110, 110', 110") having a main portion (114, 115, 114', 115', 114", 115") defining an axial extension (E1, E2, E1', E2', E1", E2"), the main body (11, 11') of the head (10, 10') having a certain length (L, L') along the longitudinal axis and the main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110") extending across a major part of said length (L, L') of the main body (11, 11'); * a heating device (12, 12') designed to heat the cosmetic product loaded on the applicator head (10, 10'), the heating device comprising a heating element (120, 120', 120") extending through the inside of said groove (110, 110', 110"), the heating element comprising a resistance wire (120, 120', 120") having a main portion (121, 122, 121', 122', 121", 122") extending along the axis of extension (E1, E2, E1', E2', E1", E2") of the main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110") across the entire length of said main portion (114, 115, 114', 115', 114", 115") of the groove (110, 110', 110").