Zyra's ult and damage

Im curious I do like the new rework of zyra but there was something that caught my eye if all of zyras abilities except her ult can summon her plants then why cant her ult be able to summon her plants and I mean a different variety she suppose to be able to summon predator plants and if that's the case then why doesent her ult do it I mean that when her plants are suppose to be at there strongest and yet the only thing it does is knock them up to ne honest I think its a design flaw and she should be able to summon her plants with her ult and the plant that the seeds summon for her ult should be different than the ones she can currently summon I mean it only makes sense to the design of her character, but I also feel as though her plants are lacking in some damage and to her Ap for some reason spell vamp does not apply to her plants

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