▁is ▁a ▁natural ▁crossing ▁of ▁two ▁virt ually ▁ext inct ▁B ale ar ic ▁g rap es , ▁Sab at é ▁and ▁Cal let ▁Cas ▁Con cos ▁which ▁would ▁make ▁the ▁gra pe ▁a ▁half - s ib ling ▁to ▁Cal let ▁( its elf ▁a ▁cross ▁of ▁Cal let ▁Cas ▁Con cos ▁and ▁F og one u ). ▁Additionally , ▁Cal let ▁Cas ▁Con cos ▁is ▁believed ▁to ▁be ▁a ▁natural ▁crossing ▁of ▁the ▁S ardin ian ▁wine ▁gra pe ▁Gir ò ▁and ▁the ▁Spanish ▁wine ▁gra pe ▁B eb a ▁which ▁would ▁make ▁M anto ▁negro ▁a ▁grand child ▁to ▁these ▁vari eties . ▁ ▁Despite ▁sharing ▁the ▁syn onym ▁Mant uo , ▁the ▁gra pe ▁is ▁not ▁a ▁color ▁mut ation ▁nor ▁does ▁it ▁have ▁any ▁known ▁relationship ▁with ▁the ▁white ▁Spanish ▁wine ▁gra pe ▁Ch el va ▁which ▁is ▁known ▁as ▁Mant ú o ▁in ▁Ext rem ad ura . ▁ ▁Vit icult ure ▁ ▁M anto ▁negro ▁is ▁a ▁late - ri pen ing ▁gra pe ▁variety ▁that ▁bud s ▁early ▁in ▁the ▁growing ▁season ▁and ▁produces ▁average ▁size ▁clusters ▁of ▁large , ▁thick - sk inned ▁g rap es . ▁The ▁v ine ▁often ▁does ▁not ▁go ▁through ▁ver aison ▁completely ▁with ▁some ▁ber ries ▁on ▁a ▁cluster ▁never ▁getting ▁dark er ▁than ▁a ▁pale ▁p ink ▁sh ade . ▁In ▁rich ▁and ▁fert ile ▁so ils ▁the ▁variety ▁can ▁be ▁very ▁product ive ▁and ▁high ▁yield ing ▁with ▁the ▁v ine ▁performing ▁best ▁in ▁st ony