how to add to matrix in a loop rather than replace

I like to use the following codes to put members in groups. But as you can see Alkanes are replaced not added up.

species{1}=[0.86 1.27 1.23]; species{2}=[1.4]; species{3}=[4.32 3.49 1.33 1.02 0.83]; species{4}=[8.87 6.89 6.78 6.74 6.72 3.73];

type{1}=['aliohatic' 'aliphatic' 'aliphatic']; type{2}=['cycloalkene']; type{3}=['aliphaticOH' 'alcoholethyl' 'aliphatic' 'aliphatic' 'aliphatic']; %13=aliphaticOH %14=alcoholethyl type{4}=['ArOH' 'aromaticH' 'aromaticH' 'aromaticH' 'aromaticH' 'ArOCH3'] %15=ArOH %16=aromaticH %17=ArOCH3

for iC=1:4 if ismember('ArOH', type{iC}) parent{iC}='Phenols' Phenols=species{iC}

        elseif ismember('aliphaticOH', type{iC})
        parent{iC}='Alcohols'
        Alcohols=species{iC} 

        elseif ismember('cycloalkene', type{iC}) 
            parent{iC}='Alkanes'

        elseif ismember('aliphatic', type{iC}) 
            parent{iC}='Alkanes'
            Alkanes=species{iC}

        else
            parent{iC}='unknown'         
        end
end